Skip to content

Mixing Ratio Calculator

Split a batch of resin into part A and part B for any ratio, by volume and by weight, with the percentage each part takes.

A ratio is easy to read and surprisingly easy to get wrong when the batch is small. This calculator takes the ratio you mix to and the amount of resin you need, then gives you part A and part B in millilitres and in grams, along with the percentage of the batch each part represents. It is a planning and costing tool, and the ratio to use is the one your manufacturer specifies for your product.

At a glance

What you enter
Common ratio, Part A in the ratio, Part B in the ratio, Total mixed resin you need, Density of part A, Density of part B
What you get
Part A by volume, Part B by volume, Part A by weight, Part B by weight, Part A as a percentage, Part B as a percentage, Weight of the whole batch, Density of the mixed resin
Formula shown
Yes, every step, right below your results.
Cost and privacy
Free, no account needed, and nothing you type is stored.

See worked examples โ†“ Read the FAQ โ†“ Share this calculator โ†“

Common ratio

A convenience list. The two ratio numbers below are what the calculation actually uses, so set them to whatever your product specifies.

The first number of the ratio. For 2:1 enter 2 here and 1 below.

The second number of the ratio.

Resin is often near 1.1 to 1.2 grams per millilitre. Check the technical data sheet for your product.

Hardener is often slightly less dense than resin, near 0.95 to 1.05 grams per millilitre.

Reset

Results are estimates for general information only, always verify with a professional or official source before acting on them.

How to use the Mixing Ratio Calculator

  1. 1 Enter Common ratio, A convenience list. The two ratio numbers below are what the calculation actually uses, so set them to whatever your product specifies.
  2. 2 Enter Part A in the ratio, The first number of the ratio. For 2:1 enter 2 here and 1 below.
  3. 3 Enter Part B in the ratio, The second number of the ratio.
  4. 4 Enter Total mixed resin you need (ml)
  5. 5 Enter Density of part A (g/ml), Resin is often near 1.1 to 1.2 grams per millilitre. Check the technical data sheet for your product.
  6. 6 Enter Density of part B (g/ml), Hardener is often slightly less dense than resin, near 0.95 to 1.05 grams per millilitre.
  7. 7 Press Calculate. You get Part A by volume, Part B by volume, Part A by weight, Part B by weight, Part A as a percentage, Part B as a percentage, Weight of the whole batch, Density of the mixed resin, and every intermediate step stays visible under "How is this calculated?"
  8. 8 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.

Worked examples

Real numbers run through this calculator. Open any example to load it into the form above and change it.

300 ml batch at 2:1

A 2:1 mix by volume, 300 millilitres in total, with part A at 1.15 and part B at 1.0 grams per millilitre.

You enter

Common ratio
2
Part A in the ratio
2
Part B in the ratio
1
Total mixed resin you need
300 ml
Density of part A
1.15 g/ml
Density of part B
1 g/ml

You get

Part A by volume
200.00 ml
Part B by volume
100.00 ml
Part A by weight
230.00 g
Part B by weight
100.00 g
Part A as a percentage
66.67 %
Part B as a percentage
33.33 %
Weight of the whole batch
330.00 g
Density of the mixed resin
1.10 g/ml

200 millilitres of part A and 100 of part B, which weigh 230 grams and 100 grams, so the batch is 330 grams.

Open this example in the calculator โ†’

Small 30 ml batch at 1:1

A 1:1 mix for a couple of small pieces, where the tolerance matters more.

You enter

Common ratio
1
Part A in the ratio
1
Part B in the ratio
1
Total mixed resin you need
30 ml
Density of part A
1.15 g/ml
Density of part B
1 g/ml

You get

Part A by volume
15.00 ml
Part B by volume
15.00 ml
Part A by weight
17.25 g
Part B by weight
15.00 g
Part A as a percentage
50.00 %
Part B as a percentage
50.00 %
Weight of the whole batch
32.25 g
Density of the mixed resin
1.08 g/ml

15 millilitres of each part, about 17.3 grams of A and 15 grams of B. This is a small enough batch that a household scale is the weak point.

Open this example in the calculator โ†’

Frequently asked questions

How do I split a 2:1 mix into the two parts?
Add the two numbers together to get three, then give part A two of those three parts and part B one. For a 300 millilitre batch that is 200 millilitres of part A and 100 millilitres of part B. In percentages, part A is 66.7 percent and part B is 33.3 percent. A 3:1 mix works the same way with four parts, giving three quarters to part A.
Is a 1:1 ratio by weight the same as 1:1 by volume?
No, unless the two parts happen to have the same density, which they usually do not. Resin is often near 1.15 grams per millilitre and hardener near 1.0, so equal volumes do not weigh the same. Mix to the wording your manufacturer uses and do not convert one into the other by assuming the parts weigh the same.
What happens if the ratio is slightly wrong?
A small error usually shows up as a batch that stays tacky, cures softer than it should or feels slightly waxy rather than hard. Too much hardener is not a safe correction for too little, because unreacted hardener is itself a skin sensitiser and can leave the surface permanently sticky. Mix the ratio the data sheet specifies and measure it properly rather than adjusting by feel.
How accurate does my scale need to be?
Better than one gram, and preferably to 0.1 grams, for small batches. On a 300 millilitre batch at 2:1, one millilitre of error in part B is about a third of a percent, which is harmless. On a 30 millilitre batch the same error is over three percent, which is not. Scale the batch up rather than trying to measure a tiny one precisely.
Do I need to account for the resin left in the cup?
Yes, and it is the reason the waste allowance exists elsewhere in these tools. A measurable amount of the batch coats the walls of the mixing cup and the stirrer and never reaches the mould, and the proportion is larger on a small batch than a big one. Mixing ten to fifteen percent more than the mould needs is normal practice.

More money questions answered โ†’

Terms used here

Short, plain-language definitions of the words this calculator uses.

Share this tool

Send the calculator, or your exact numbers, to whoever needs to see them.

Your browser blocked the clipboard, select the link above and copy it manually.

Embed this calculator on your own site โ†’

We use essential cookies to run this site. Optional partners (advertising and analytics) only load if you accept them. See our Privacy Policy.