Mixing Ratio Calculator (concentrate, 2-stroke oil, epoxy)

Understanding the mixing ratio calculator — concept and principle

This calculator splits an amount into two ingredients by a ratio such as 1:10, or works out the rest of a mix when you know one part. It is used for diluting cleaning concentrates, mixing epoxy and hardener, two-stroke fuel, fertiliser, paint and drinks.

Split into equal parts: with the default inputs the result is 90.91 + 909.09 (A is 9.09% of the mix).

How it is calculated

For a ratio A : B:

If you know the total: one part = total ÷ (A + B).
If you know the amount of A: one part = amount ÷ A; if you know B: one part = amount ÷ B.
Amount of A = A × one part; amount of B = B × one part.
A as a share of the mix = A ÷ (A + B).
"1 part A to … parts B" = B ÷ A; "1 in N" = (A + B) ÷ A.

The principle

A ratio describes parts, not amounts. 1:10 means one part of A for every ten parts of B, so the whole mix has eleven parts and A is 1/11 of it. Once you know how big one part is, everything else follows by multiplication. Labels sometimes say "1:10" and sometimes "1 in 11" for the same mix, which is why the calculator shows both. The result uses whatever unit you typed, whether millilitres, litres or grams.

Worked example

Default inputs: ratio 1:10, total to make 1,000.

Total parts = 1 + 10 = 11; one part = 1,000 ÷ 11 = 90.91.
A = 1 × 90.91 = 90.91; B = 10 × 90.91 = 909.09.
Total = 1,000.
A as a share = 1 ÷ 11 = 9.09%.
"1 to 10" parts, or "1 in 11".

Each point is the calculator re-run with only “Ratio: parts of B (e.g. water, petrol, resin)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Ratio: parts of B (e.g. water, petrol, resin)	Amount of A
2.5	285.71
5	166.67
7.5	117.65
10	90.91
12.5	74.07
15	62.5
20	47.62

How to read the result

Check whether the label means 1:10 (1 + 10) or 1 in 10 (1 + 9); the difference is about 10% in strength. Mix by volume or by weight as the product says, because liquids of different densities give different results. For two-part resins, accurate ratios matter a lot; measure carefully.

Common mistakes

Treating 1:10 as one part in a total of 10.
Mixing by volume when the product specifies weight.
Using different units for the two parts.
Rounding very small amounts too much.

Keep in mind: Follow the product label for ratios and safety. Never mix chemicals such as bleach and ammonia-based cleaners.

Frequently asked questions

How much concentrate for 1 L at 1:10?

About 91 mL of concentrate and 909 mL of water.

Is 1:10 the same as 1 in 10?

No. 1:10 is 1 part in 11 total; 1 in 10 is 1 part in 10 total.

How do I mix if I know only the amount of concentrate?

Choose "amount of A", and the calculator works out B and the total.

Sources: OpenStax, Prealgebra 2e (2020), §6.5 "Solve Proportions and their Applications"

Checked 9 Nov 2026. Ratio and proportion (parts of a whole), as in any school mathematics text, e.g. OpenStax Prealgebra 2e (2020), §6.5 “Solve Proportions and their Applications”.

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