From measured space to purchasable material
Some coating systems specify a base-to-hardener ratio and a permitted thinner addition. This calculator converts a desired ready-to-use batch volume into the separate component volumes. You can define thinner as a percentage of the combined base and hardener or as a percentage of base alone, which are different instructions and yield different amounts. Ratios here are by volume, never by weight. Use only the exact ratios, permitted solvent, and application limits specified for your product. The calculator handles arithmetic and does not determine chemical compatibility, ventilation, pot life, or safe handling requirements.
Measure, select yield and round the order
- Read the product mixing ratio and confirm that it is specified by volume.
- Choose the basis stated for the optional thinner percentage.
- Measure the calculated components using suitable marked containers and follow the product mixing process.
Net requirement and purchase calculation
A worked example
For one gallon ready to use, a 4:1 base-to-hardener ratio and thinner at 10% of combined components require 0.72727 gallons base, 0.18182 gallons hardener, and 0.09091 gallons thinner.
Coating Mix Ratio: what changes the result?
Check how the chosen product changes the order. The comparisons below are calculated from this page’s default example. Each row changes only the named input; all other inputs stay at their displayed example values. These are mathematical scenarios, not measurements from a completed project.
| Changed assumption | Default input | Comparison input | Result: default → comparison |
|---|---|---|---|
| Desired ready-to-use batch | 1 US gal | 1.2 US gal | Base component volume: 0.7273 → 0.8727 US gal Hardener component volume: 0.1818 → 0.2182 US gal |
| Base ratio parts | 4 | 4.8 | Base component volume: 0.7273 → 0.7524 US gal Hardener component volume: 0.1818 → 0.1567 US gal |
| Hardener ratio parts | 1 | 1.2 | Base component volume: 0.7273 → 0.6993 US gal Hardener component volume: 0.1818 → 0.2098 US gal |
| Thinner percentage | 10 % | 12 % | Base component volume: 0.7273 → 0.7143 US gal Hardener component volume: 0.1818 → 0.1786 US gal |
Displayed values are rounded. Whole-pack results change in steps; continuous quantities may change before a new pack is needed. To compare your actual project, enter your dimensions above, save a scenario, then change one assumption.
Coverage, allowance and purchasing limits
- A four-to-one volume ratio is not a four-to-one weight ratio unless the component densities happen to match.
- The tool does not recommend a thinning percentage; enter zero when the product does not permit thinning.
- Make only a batch compatible with the product pot life and application conditions.
Frequently asked questions
How much hardener for a 4 to 1 paint mix?
Hardener is one quarter of the base volume. If you target a final batch including thinner, first remove the thinner portion using the correct percentage basis.
Is 10 percent thinner based on mixed paint or base?
The product instructions determine that. The calculator supports both bases because they give different component amounts.
Can I calculate a weight-based epoxy mix?
No. This tool is explicitly for volume ratios; weight ratios require component masses and should be measured as specified.
Calculation method: JICWH methodology. Examples are planning assumptions, not product recommendations.