What is the Coolant Mix Ratio Calculator?
Engine coolant (antifreeze) protects your cooling system from freezing in winter and boiling in summer while resisting corrosion. Most concentrate must be diluted with water — typically to a 50/50 blend. This calculator tells you exactly how many liters of antifreeze concentrate and how many liters of water to combine for any total system volume and target concentration.
How to use it
Enter your total coolant capacity in liters (check your owner's manual for the cooling system capacity) and the antifreeze concentration you want as a percentage. The calculator splits the total into the concentrate and water amounts and shows the resulting antifreeze-to-water ratio.
The formula explained
The antifreeze volume is simply the total multiplied by the fraction you want as concentrate: $$\text{A} = \text{V} \times \frac{\text{P}}{100}$$ Whatever volume is left is water: $$\text{W} = \text{V} - \text{A}$$ For example, a 50% mix means half concentrate, half water — a classic 1:1 ratio.
Worked example
Suppose your system holds 10 liters and you want a 50% mix. Antifreeze = \(10 \times \frac{50}{100} = 5\) liters. Water = \(10 - 5 = 5\) liters. That is a 1:1 ratio — perfect for typical climates with protection to roughly −37 °C.
FAQ
Should I use distilled water? Yes. Distilled or deionized water avoids mineral deposits and corrosion that tap water can cause.
Can I use pre-mixed coolant? Pre-mixed (ready-to-use) coolant is already diluted, usually to 50%, so you add it directly without extra water. This calculator is for concentrate.
What concentration should I choose? 50% is standard. Going up to ~60–70% increases freeze protection but excessive concentrate actually reduces freeze and heat-transfer performance, so stay within manufacturer limits.
