Paint Mixing Ratio Calculator

Calculate how much thinner, conditioner, or water to add to a base paint quantity, in fluid ounces and tablespoons.

Additive
— fluid ounces
To mix in.

Usage Tip

Add the conditioner gradually and stir well; too much thins the paint and weakens coverage.

THE MATH
additive volume = base paint × (ratio ÷ 100)
Additives like conditioner, thinner, or water are mixed into paint as a percentage of the base volume. This converts that percentage into fluid ounces and tablespoons.
Enter the base paint amount in gallons and the additive ratio.
Floetrol is usually 5 to 10 percent; washes and limewash use much more water.
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The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.