Acrylic Pouring Ratio Calculator: Mix Every Cup Right

Fluid acrylic pouring lives or dies on the paint to medium ratio, and most wasted paint comes from mixing cups by eye and running short halfway through a 40×50 cm canvas. This calculator takes the number of colours you plan to pour, the ratio you want, and either the paint you have per cup or the total volume you need, then returns the exact millilitres of paint and pouring medium for each cup, the total mixture, the silicone dose, and the canvas area that volume will actually cover.

It works in two directions. If you already know you want 30 ml of paint in each cup, it tells you how much medium to add and what you end up with. If you know the canvas needs roughly 560 ml of mixture, it works backwards and tells you how much paint sits inside that number once the medium is accounted for. The second direction is the one that saves money, because paint is the expensive half of the cup and medium is the cheap half.

Everything is in millilitres, and the coverage figure is in square centimetres of canvas at a wet layer of about 2.8 mm. Nothing here is a cost tool, so bring your own prices; what you get is volume, dosage and area.

✂️ How to use the Acrylic Pouring Ratio calculator

Start with the two tabs at the top, because they change which volume field you see. By paint/colour assumes you are measuring paint into each cup and want to know the medium that goes on top. By total volume assumes you know the finished mixture you need for the surface and want the calculator to split it back into paint and medium.

Lisa Mandel

Set the number of colours next. This is the count of separate cups you will mix, not the count of pigments in a dirty pour: if you plan white, teal, black and a metallic gold, that is 4, which is the default. The per-colour table at the bottom grows and shrinks with this number, so a 7-colour flip cup gives you 7 rows.

In the By paint/colour tab, the field below is Paint per colour (ml), default 30. Thirty millilitres is roughly a heaped tablespoon of craft acrylic and is the classic amount for a small dirty pour cup. In the By total volume tab, that field is replaced by Total mixture wanted (ml), default 300, stepping in tens.

Then set the ratio. Four preset buttons sit above the field (1:1, 1:1.5, 1:2, 1:3) and each writes a number into the box: 1, 1.5, 2 and 3. The number is parts of medium per one part of paint, so 1.5 means one part paint to one and a half parts medium. You can type any value you like, in steps of 0.1, which matters when a heavy-bodied white needs 2.4 and a thin fluid teal only needs 0.8.

Type the ratio your paint asks for, not the ratio your last video used. A student-grade heavy body and a professional fluid acrylic can sit two whole parts apart on the same brand of Floetrol.

Last come the silicone controls. Add silicone for cells? is a Yes or No select, defaulting to Yes. When it is set to Yes, a second field appears asking for Silicone drops per 30 ml, default 2, and a red warning about varnish shows under the results. Switching it to No removes the drops field, the drops tile and the warning, which is what you want for a plain sheen pour or any layer you intend to paint over later.

Read the results on the right as you type. Nothing needs submitting, and the per-colour table updates on every keystroke, so you can nudge the ratio from 1.5 to 1.8 and watch the total mixture and the covered area move together.

📋 Calculator fields explained

Mode tabs (By paint/colour, By total volume) – the two ways into the same maths. The first treats paint per cup as the fixed quantity and builds the total upwards. The second treats the finished mixture as the fixed quantity and divides it back into paint and medium. Default is By paint/colour.

Number of colours – how many separate cups you are mixing, in whole steps. Default 4. This multiplies the per-cup mixture into the total, and it also decides how many rows appear in the breakdown table.

Paint per colour (ml) – visible only in the By paint/colour tab. The undiluted acrylic you put in each cup before any medium, in millilitres, stepping by 1. Default 30.

Total mixture wanted (ml) – visible only in the By total volume tab. The finished poured volume you need across all cups, paint and medium combined, stepping by 10. Default 300.

Medium : paint ratio – parts of pouring medium per single part of paint, stepping by 0.1, default 1.5. The four preset buttons above it write 1, 1.5, 2 and 3. Higher numbers mean a thinner, faster flowing mix that spreads further and cells more readily, and a weaker pigment load.

Add silicone for cells? – a Yes or No select, default Yes. Yes turns on the drops field, the drops result tile and the varnish warning. Pick No for pours that will be sealed with resin without a wash, or for base layers you plan to paint over.

Silicone drops per 30 ml – appears only when silicone is set to Yes. Drops of silicone oil per 30 ml of finished mixture, stepping by 1, default 2. The calculator scales this against the total mixture, not against the paint alone.

📊 Understanding the results

The green hero number is Total mixture. That is the figure that decides whether the pour succeeds, because a canvas that needs 560 ml and receives 300 ml ends up with dry corners and a panicked second batch mixed in a hurry at a slightly different consistency. Read it first, compare it with the coverage tile, and only then look at the per-cup detail.

Mixture per colour is the number you need at the table. With the defaults (4 colours, 30 ml paint, ratio 1.5) each cup holds 75 ml: 30 ml of paint and 45 ml of medium. Four of those give 300 ml total, and 300 ml at 0.28 ml per cm² covers about 1071 cm², which is a 30×35 cm canvas with almost nothing spare.

The coverage number assumes a 2.8 mm wet layer and no run-off, and that second half is where people lose paint. A tilted canvas sheds a real amount over the edges, often a fifth of everything you poured, and that paint is on the drip tray rather than on the surface.

Coverage is calculated as a perfectly even skin. Anything you tilt, swipe or flip will bleed off the sides, so treat the cm² figure as an upper limit and add 20 to 30 percent for a heavy tilt.

The per-colour table repeats the same three numbers on every row, which looks redundant until you are standing over eight cups with wet gloves on. It is a measuring sheet, not an analysis. Read row four, pour row four, move on.

The silicone drops tile counts the whole batch, not one cup. With the defaults it reads 20, which is 300 ml divided by 30, multiplied by 2. You then divide those 20 drops across your cups by hand, and most pourers deliberately skip the white or the black entirely so it keeps a clean, unbroken surface for the cells to sit against.

Watch the two ends of the ratio field. Push it to 3 and the paint fraction drops to a quarter of the cup, which pours like water and cells beautifully and can also dry translucent enough to show the gesso through it. Pull it back to 0.5 and you have a mix that barely moves, holds every trowel mark, and produces almost no cells at all.

In By total volume mode the per-cup paint figure is the interesting one, because it tells you whether your bottles will survive the pour. Ask for 900 ml across 3 colours at ratio 1.5 and each cup needs 120 ml of raw paint, which is most of a 4 oz bottle per colour.

🧮 Calculation formulas

Two paths lead to the same four numbers, and the ratio (call it R) sits in the middle of both.

In By paint/colour mode the paint you type is taken as given:

paint per colour = the value you entered
medium per colour = paint per colour x R
mixture per colour = paint per colour x (1 + R)
total mixture = mixture per colour x number of colours

In By total volume mode the arithmetic runs the other way:

mixture per colour = total volume / number of colours
paint per colour = mixture per colour / (1 + R)
medium per colour = paint per colour x R

Then, in both modes:

silicone drops = (total mixture / 30) x drops per 30 ml, or zero when silicone is set to No
coverage in cm² = total mixture / 0.28

Working the default settings through step by step: 4 colours, 30 ml of paint each, R = 1.5, silicone Yes at 2 drops per 30 ml. Medium per colour is 30 x 1.5 = 45 ml. Mixture per colour is 30 + 45 = 75 ml. Total is 75 x 4 = 300 ml. Drops are (300 / 30) x 2 = 20. Coverage is 300 / 0.28 = 1071 cm².

The 0.28 comes from geometry: one square centimetre of canvas covered in a 2.8 mm wet film holds 0.28 cm³, and one cubic centimetre is one millilitre. So each millilitre of mixture covers about 3.57 cm², and the fixed constant is why the coverage tile moves only when the total mixture moves.

The ratio also sets your pigment strength. At R = 1, half the cup is paint. At R = 3, only a quarter is, so the same white will look considerably weaker over a dark base even though the cup holds the same millilitres.

That relationship is worth having in front of you when you pick a preset, since the paint fraction is 1 divided by (1 + R):

And because the coverage constant never changes, the volume a given canvas needs can be read straight off a table. Multiply the canvas area in cm² by 0.28 to get the millilitres, then type that into the By total volume tab.

🎨 Practical examples

1. First dirty pour on a 30×35 cm canvas. By paint/colour, 4 colours, 30 ml each, ratio 1.5, silicone Yes at 2 drops. Each cup takes 30 ml paint and 45 ml medium for 75 ml. Total 300 ml, 20 drops, coverage 1071 cm². The canvas is 1050 cm², so it fits with 21 cm² to spare, which in practice means a tight pour with no tilting margin. Add a fifth cup or bump the paint to 35 ml per colour.

2. Small 10×10 cm practice tile. By total volume, 100 ml, 3 colours, ratio 2, silicone Yes at 2 drops. Each cup is 33.3 ml, of which 11.1 ml is paint and 22.2 ml is medium. Total 100 ml, 7 drops, coverage 357 cm². Three tiles of 100 cm² each come out of that batch, which is the cheapest way to test a new medium.

3. Thick, colour-heavy swipe. By paint/colour, 5 colours, 40 ml each, ratio 1, silicone Yes at 2 drops. Medium is also 40 ml, cups hold 80 ml, total 400 ml, 27 drops, coverage 1429 cm². The 50/50 mix holds its edges under the swipe card instead of running out from under it.

4. Cell-hunting thin pour. By paint/colour, 4 colours, 20 ml each, ratio 3, silicone Yes at 3 drops. Medium per cup is 60 ml, cups hold 80 ml, total 320 ml, 32 drops, coverage 1143 cm². Only 80 ml of actual paint produced 1143 cm² of coverage, which is why thin pours feel cheap right up until they dry patchy over a mid-grey ground.

A pourer who mixes 300 ml for a 2000 cm² canvas has not made a small painting. They have made a canvas with a bald patch and a bill for a second bottle of white.

5. Large 40×50 cm commission. By total volume, 560 ml, 6 colours, ratio 1.5, silicone Yes at 2 drops. Each cup is 93.3 ml: 37.3 ml paint and 56 ml medium. Total 560 ml, 37 drops, coverage exactly 2000 cm². Because a canvas that size is almost always tilted hard, mix at 700 ml instead and accept the overflow into the tray.

6. Batch of 12 coasters, 10×10 cm each. Total area 1200 cm², so By total volume with 336 ml, 4 colours, ratio 2, silicone Yes at 2 drops. Each cup is 84 ml: 28 ml paint, 56 ml medium. Total 336 ml, 22 drops. Silicone here is a nuisance later, since every coaster gets sealed, so many makers set the select to No and lose the cells rather than wash 12 pieces.

7. Market stock run of eight 20×20 cm panels. Area is 3200 cm², so the mixture is 896 ml. By total volume, 896 ml, 5 colours, ratio 1.5 gives 179.2 ml per cup, of which 71.7 ml is paint. That is 358 ml of raw acrylic across the batch, and knowing it before you start is the difference between one shopping trip and two.

8. Silicone off, resin on. Any of the above with Add silicone set to No. The drops tile disappears, the drops figure is zero, and the red warning about varnish goes away. Use this whenever the piece will be resined without a soap wash, because silicone under resin produces fisheyes that no amount of torching will close.

9. Medium substitution edge case. You planned Floetrol at ratio 1.5 but only have a professional pouring medium that runs much thinner. Drop the ratio to 0.8 and keep the paint at 30 ml per colour: cups fall to 54 ml, four of them give 216 ml, and coverage drops to 771 cm². Either add a fifth and sixth colour or step down to a smaller canvas.

💡 Tips and best practices

Mix in cups that hold at least half again what the calculator says. A 75 ml mixture in an 80 ml cup will climb the sides the moment you stir it, and the paint you lose on your stick and your fingers is real paint.

Measure the paint first and the medium second, always in that order. Paint clings to the cup wall and reads high if you pour it onto medium, and the ratio you actually mixed drifts away from the ratio on screen.

Set the ratio per colour, not per project. Titanium white and carbon black are usually the two heaviest paints on the table and want more medium than a phthalo. Run the calculator twice with different ratios if the difference is more than half a part, and note the two totals separately.

Keep one colour silicone-free. A clean white or black under the silicone-loaded colours gives the cells a solid background to open against, and it saves that colour for any layering you do later.

Stir slowly and stop stirring. Whipped air is the main cause of pinholes that appear an hour into drying, and a fast stir on a 40 ml cup can hold enough bubbles to ruin a whole quadrant. Let mixed cups stand for 20 to 30 minutes if you have the time.

Do a lift test before you trust a new ratio. Lift the stick and let the mixture run back into the cup: it should reform into the surface in about four seconds. Faster than two seconds is too thin, and the calculator has no way to know how thin your paint was to begin with.

Round the total mixture up to the next 50 ml when you are tilting, flipping or swiping. The coverage figure describes a flat, even film, and none of those techniques produce one.

Add the silicone last, after the medium is fully blended, and stir it three times only. Over-stirred silicone breaks into droplets too small to make visible cells and the whole dose is wasted.

Write the ratio on the cup with a marker. Two days later, when one panel cells and another does not, the cups are the only record of what you actually did.

For repeat work, save the volumes rather than the settings. If a 30×40 cm canvas at 5 colours came out right at 420 ml, that number is now yours; type it into the By total volume tab every time and let the calculator resplit it whenever you change medium.

⚠️ Common mistakes to avoid

Reading the ratio backwards

The presets say 1:3 and the field takes 3. That 3 is medium, not paint. Someone typing 3 while thinking three parts paint to one part medium ends up with a cup that is three quarters medium, and the colour dries pale and translucent.

Entering 3 when you meant 0.33 puts nine times too much medium in the cup and every colour on the canvas will dry weak enough to show the gesso.

The per-colour table catches this instantly. If the Medium column is bigger than the Paint column and you did not intend a thin mix, fix the ratio before you open a single bottle.

Ignoring the tilt loss

The coverage tile is a flat-film number. Mixing exactly 336 ml for a 30×40 cm canvas and then tilting it aggressively leaves you short, because a fifth of that volume is now on the drip tray. A hard tilt can lose 25 percent of the mixture over the canvas edges, which is the single most expensive mistake in this list.

Counting pigments instead of cups

Number of colours means cups. A dirty pour that combines white, gold and two blues into one cup and pours it in a single stream is four pigments and one cup only if you mix them together, and four cups if you mix them separately. Entering 4 when you will only mix 1 quadruples the total and the shopping list with it.

Silicone in every cup

The drops figure is a total for the whole batch, and pourers routinely split it evenly across every cup. That gives cells everywhere and a canvas with no calm areas, and it also contaminates the one colour you might have wanted to varnish later.

Splitting the batch dose across all colours produces uniform cell noise, and it removes any surface you could safely paint or seal over afterwards.

Load two or three colours heavily, leave the rest clean, and the cells will have somewhere to open.

Sealing over unwashed silicone

The red warning is there because silicone repels varnish and resin. A cured piece with silicone still on the surface will bead the sealer into fisheyes, and no second coat repairs it. Wash the cured piece with warm water and dish soap, dry it fully, and only then seal.

Mixing one giant cup for many colours

The calculator assumes the number of colours you enter is the number of separate mixes. Mixing 300 ml as a single cup and then dividing it by eye means each of the four colours got a different amount of medium and a different amount of paint, and the ratio on screen described none of them.

Trusting the coverage number on an absorbent surface

Raw wood, unprimed board and porous plaster drink the first millilitres before any film forms. The 0.28 ml per cm² constant assumes a sealed surface, so gesso the board first or add 15 percent to the total.

🎯 When to use this calculator

Open it when you are about to buy paint. The By total volume tab is the only way to see how much raw acrylic actually sits inside a poured surface, and the answer for a 50×70 cm canvas at ratio 1.5 is 392 ml of paint, which is a shopping decision rather than a studio one.

Open it when you change medium. Floetrol, PVA-based mixes and professional pouring mediums all sit at different working ratios, and the totals move with them. A ratio change from 1.5 to 2 on a 4-colour, 30 ml pour lifts the total from 300 ml to 360 ml and the coverage from 1071 cm² to 1286 cm², which may turn a canvas that did not fit into one that does.

Open it when you are producing a batch for sale, because eight panels is eight chances to run out at the seventh. Working out the total once, at the start, is faster than mixing a rescue cup with a slightly different consistency and watching the seam show up as the piece dries.

The cup does not care how confident you were about the ratio. It only knows how much medium you put in it.

Leave it closed for the small stuff. If you are pouring a 10×10 cm tile with two cups you already mixed for a previous project, the answer is on the table in front of you. The calculator earns its keep on anything above 20×25 cm, on anything with more than four cups, and on any surface you cannot afford to redo.

🔗 Related calculators

Cell Silicone Drops

Paint Thinning Ratio

Paint Coverage

Acrylic Drying Time

Gesso Quantity

Canvas Cost

Color Mixing Ratio

Painting Pricing

📖 Glossary

Pouring medium – an additive that thins acrylic paint while keeping the binder intact, so the colour flows without losing adhesion or gloss. Floetrol, GAC 800 and dedicated pouring mediums all qualify.

Ratio (R) – in this calculator, the parts of medium per single part of paint. R = 2 means two parts medium to one part paint.

Paint fraction – the share of the cup that is undiluted paint, equal to 1 / (1 + R). At R = 1.5 it is 40 percent.

Dirty pour – several colours layered into one cup and poured together, so they emerge in bands.

Flip cup – a dirty pour cup inverted onto the canvas and lifted, releasing the layers at once.

Swipe – dragging a card or palette knife across wet colours to stretch cells into a directional pattern.

Cell – a round opening where a denser colour sinks and a lighter one rises through it, usually encouraged by silicone oil or a density difference between paints.

Do cells need silicone? No. Density differences between paints, a torch and the right ratio will produce them, but silicone makes them larger, rounder and far more reliable.

Silicone oil – a low-surface-tension oil, often 100 percent dimethicone, dosed in drops to break the paint film open into cells.

Wet layer thickness – the depth of mixture sitting on the canvas before it dries. This calculator assumes 2.8 mm.

Coverage constant – the 0.28 ml per cm² used here, derived from the 2.8 mm layer.

Tilt loss – the share of mixture that runs off the canvas edges during tilting, commonly 15 to 30 percent.

Crazing – a fine cracked surface caused by too much medium, too thick a layer, or drying too fast.

Fisheye – a circular void in varnish or resin caused by residual silicone repelling the coating.

Heavy body acrylic – thick, paste-like paint that typically needs more medium than a fluid acrylic to reach the same consistency.

❓ Frequently asked questions

What ratio should I start with?

The 1:1.5 preset (R = 1.5) is the default for a reason. It gives a 40 percent paint fraction, flows well enough for a flip cup, and still dries opaque over white gesso.

If your paint is a heavy body craft acrylic, expect to push it to 2 before it moves properly. If it is already a fluid acrylic, 1 is often plenty, and pushing to 3 will produce a translucent film that looks convincing while wet and disappointing when dry.

Why does the calculator use 2.8 mm?

It is a workable average for a poured layer that is thick enough to level itself and thin enough not to crack while drying. That translates to 0.28 ml of mixture per square centimetre, or 3.57 cm² per millilitre.

The figure is fixed in the tool and cannot be changed from the interface. If you pour deliberately thin at around 2 mm, your real coverage will be about 40 percent higher than the tile shows, and if you flood a piece at 4 mm it will be roughly 30 percent lower.

How many silicone drops is too many?

Two drops per 30 ml is the default and produces visible cells in most paints. Three to four is aggressive and gives large, overlapping cells that can eat the composition.

Above about six drops per 30 ml the paint film starts breaking rather than opening, leaving crater edges instead of round cells, and the wash-off afterwards becomes a chore across the whole surface.

Silicone dosing is one of the few places in pouring where less genuinely does more. Start at 2, look at the dry result, and only then decide whether the cells were too shy.

The drops tile says 20, but I have 4 cups. Do I put 5 in each?

You can, and many people do. The 20 is a batch total, calculated from the whole 300 ml of mixture and not from any individual cup.

The common alternative is loading 8 drops into two colours, 4 into a third, and none into the white. That gives cells with a clean background and a colour you can still varnish without a wash.

Can I use this for resin instead of acrylic?

No. The ratio here describes paint and pouring medium, both of which are water-based and mix in any proportion you like. Epoxy resin has a fixed chemical ratio, usually 1:1 or 2:1 by volume or weight, and getting it wrong leaves the piece permanently tacky.

The one useful crossover is the coverage figure: 0.28 ml per cm² is a reasonable flood coat for resin too, so a 30×40 cm piece needs roughly 336 ml of mixed resin.

Why does the total change when I switch tabs?

The two tabs hold different inputs fixed. By paint/colour holds the paint per cup fixed and lets the total grow with the ratio, so raising R from 1.5 to 2 lifts a 4-colour, 30 ml batch from 300 ml to 360 ml.

By total volume holds the finished mixture fixed and shrinks the paint inside it instead. The same 300 ml at R = 3 contains only 75 ml of paint, against 120 ml at R = 1.5.

Does the number of colours change the coverage?

In the By paint/colour tab, yes. Each colour adds a whole cup, so going from 4 to 6 colours at 30 ml and R = 1.5 lifts the total from 300 ml to 450 ml and the coverage from 1071 cm² to 1607 cm².

In the By total volume tab, no. The total is fixed by you, so adding colours simply divides the same volume into more, smaller cups. Six colours out of 300 ml gives 50 ml each, and 50 ml is a thin cup to pour from.

What happens if I enter 1 colour?

The calculator works normally and gives you a single row in the table. It is the right setting for a single-colour flood, a base coat, or a one-cup mix you intend to divide by eye later.

One colour at 100 ml paint and R = 2 gives 300 ml of mixture and 1071 cm² of coverage, which is enough to flood a 30×35 cm canvas in a single tone before any pouring happens on top.

Can I mix by weight instead of volume?

The calculator works purely in millilitres, so nothing here converts to grams. Paint and medium have different densities, and a heavy body acrylic can run near 1.4 g/ml while a pouring medium sits close to 1.0.

If you prefer scales, weigh the medium (1 ml is roughly 1 g for most pouring mediums) and use a syringe or measuring cup for the paint. Mixing methods within one batch is how ratios drift.

Why is there a warning about varnish?

Silicone stays on the surface after the paint cures and repels almost every sealer, which shows up as circular voids in the varnish or resin. The warning appears whenever silicone is set to Yes.

The fix is mechanical: wash the cured piece with warm water and dish soap, rinse, and let it dry for at least 24 hours before sealing. Some pourers wash twice, because a single pass rarely lifts everything out of the deeper cells.

⚖️ Disclaimer

This calculator provides educational craft-planning estimates for acrylic pouring. The volumes, ratios and coverage figures are based on the fixed assumptions built into the tool, including a 2.8 mm wet layer at 0.28 ml per square centimetre, and they describe an idealised even film on a sealed surface.

Real results depend on the specific paint brand and body, the pouring medium, humidity, temperature, the absorbency of your substrate and the technique you use. Tilting, swiping and flipping all shed mixture over the canvas edges, and a heavy tilt can remove a quarter of the volume you mixed.

Silicone dosing, cell formation and drying behaviour vary between paint lines and between batches of the same paint. Test any new ratio or medium on a small tile before committing a large canvas or an expensive professional acrylic to it, and follow the safety and ventilation guidance printed on your own materials.