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Mixing Ratio Calculator

Split a total volume into two components at any ratio.

Your measurementsEvery assumption editable01

The resin, base or first component.

The hardener, catalyst or second component.

ComponentsCalculated live02

Result

21.33 + 10.67oz

2:1 — 21.33 oz A to 10.67 oz B

Ratio3 parts in total
2 : 1
Component A66.67% of the mix
21.333 oz
Component B33.33% of the mix
10.667 oz
Total
32 oz

This is a proportional mix, where the parts add up to the total — a 2:1 epoxy is two thirds resin and one third hardener. That is a different calculation from dilution, where the ratio is concentrate against water rather than against the finished volume.

Two-part chemistry is not forgiving of approximation. Epoxies and polyurethanes cure by reaction between the components, so an off-ratio mix does not simply cure weaker — it can stay tacky indefinitely.

Check whether your product specifies by volume or by weight. The two are only interchangeable when the components have the same density, which they usually do not.

Enter how much mixed product you need and the ratio on the tin. This is a proportional mix where the parts add up to the total — different arithmetic from dilution, where the ratio is against water rather than against the finished volume.

Why use this tool?What it does differently03

Why use this tool?

Both components

Exact volumes of each, plus the percentage split for checking against a label.

Distinguished from dilution

A 2:1 mix is two thirds and one third. A 1:2 dilution is one third and two thirds. Different calculations.

Any ratio

Including fractional ratios like 100:45 that some epoxies specify.

Volume versus weight flagged

Only interchangeable when the components have the same density, which they usually do not.

How this worksThe method04

How this mixing ratio calculator works

The parts are added to give a total, then the requested volume is divided in that proportion. A 2:1 ratio is three parts in total, so component A is two thirds and B is one third.

That is what distinguishes a proportional mix from a dilution. In a mix the parts sum to the finished volume; in a dilution the ratio is concentrate against water, so a 1:10 dilution is eleven parts in total, not ten.

Two-part chemistry is unforgiving of approximation. Epoxies and polyurethanes cure by reaction between the components, so an off-ratio mix does not merely cure weaker — it can remain tacky indefinitely.

How to use itStep by step05

How to use it

  1. Step 1: Work out how much you need

    Mixed volume. Mix less than you think and make a second batch — pot life is short.

  2. Step 2: Read the ratio

    From the product. Note whether it specifies by volume or by weight.

  3. Step 3: Measure accurately

    Graduated cups or a scale, not eye. Off-ratio epoxy may never cure.

  4. Step 4: Mix thoroughly

    Including the sides and bottom of the cup, then transfer to a second cup and mix again.

Example usageWorked figures06

Example usage

A standard 2:1 epoxy
32 oz of mixed product at 2:1 is 21.33 oz of resin and 10.67 oz of hardener — 66.67% and 33.33%.
A 1:1 product
The same 32 oz splits evenly at 16 oz each. Equal-ratio products are far more forgiving of measuring error.
An awkward ratio
100:45 on 32 oz gives 22.07 and 9.93 oz. Ratios like this are exactly why measuring by eye fails.
Frequently asked questionsCommon questions07

Frequently asked questions

How do I mix a 2:1 epoxy?

Two parts resin to one part hardener, which is two thirds and one third of the finished volume. For 32 oz that is 21.33 oz resin and 10.67 oz hardener.

Is a mixing ratio the same as a dilution ratio?

No. In a mix the parts sum to the total, so 2:1 means two thirds and one third. In a dilution the ratio is concentrate to water, so 1:10 is one part in eleven.

What happens if the ratio is wrong?

Two-part products cure by chemical reaction. An off-ratio mix can cure soft, stay permanently tacky, or fail to harden at all — it is not simply weaker.

Should I measure by volume or weight?

Whichever the product specifies. They are only interchangeable if the components have identical density, and they rarely do.

Can I mix a smaller batch?

Yes, and usually you should. Pot life is often short, and a large batch generates heat as it reacts, which shortens working time further.

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