Coolant Mix Ratio Calculator
Computes cutting fluid concentrate and water volumes for a target coolant dilution ratio.
Enter Values
Range 0–100
How to use this calculator
- Enter the total volume of mix you want to make, in litres.
- Enter the target concentration as a percentage.
- Read how much concentrate and water to combine, plus the mix ratio.
How it works
The Coolant Mix Ratio Calculator works out how much concentrate and water to mix for a target dilution — useful for soluble cutting fluids and other oil-in-water coolants.
Concentrate = total × percentage, water = total − concentrate, and the ratio is 1 part concentrate to (100/percentage − 1) parts water. Always add the concentrate to the water, not the other way around, for a stable emulsion.
Worked example
10 L at 5%. Concentrate = 0.5 L, water = 9.5 L — a 1:19 mix.
Frequently asked questions
Why add oil to water and not water to oil?
Adding the concentrate slowly into water gives a stable oil-in-water emulsion. Doing it the other way can make an unstable, inverted mix that separates.
What concentration should I use?
Follow the fluid manufacturer's recommendation for your operation — commonly around 3–10% for general machining. Check it with a refractometer in production.
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Cite this tool
Zerdly. (2026). Coolant Mix Ratio Calculator. Retrieved from https://www.zerdly.com/tools/coolant-mix-ratio-calculator/
Tip: Enter any known values to calculate the remaining results.
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