Paint thinning & reducer percentage calculator
Calculate thinner or reducer from the percentage in your product instructions. Start with paint already measured or a desired finished batch.
Checked arithmetic examples
Examples only, not product recommendations. All are by volume; totals assume additive volumes.
500 mL measured paint · add 10% of paint
500 mL paint + 50 mL thinner → approximately 550 mL total.
550 mL finished mixture · add 10% of paint
500 mL paint + 50 mL thinner → approximately 550 mL total.
400 mL paint · 4:1 paint:hardener · 10% of paint
400 mL paint + 100 mL hardener + 40 mL reducer → approximately 540 mL total.
400 mL paint · 4:1 paint:hardener · 10% of paint + hardener
400 mL paint + 100 mL hardener + 50 mL reducer → approximately 550 mL total.
Percentage basis and sources
Adding 10% of paint is different from making thinner 10% of the finished mixture. This tool supports additions to paint alone or, with hardener, additions to paint + hardener before reducer. It does not support percentages of the final mixture, weight-based instructions or density conversion.
Follow your exact product’s technical sheet for the ratio, percentage basis, compatibility and mixing order. If the basis is unclear, ask the manufacturer before calculating.
For context, KBS MAXX manufacturer directions describe the base/activator ratio separately from optional thinning. That reference is not a preset or verification of your recipe.
Manufacturer page reviewed 5 October 2026. MixByParts is independent of KBS Coatings.