Paint Thinner Ratio Calculator
Calculate the exact amount of thinner needed for your paint based on the desired ratio, and get the final mixture volume.
Formulas Used
Thinner Volume = Paint Volume × (Thinner Parts ÷ Paint Parts)
Total Mixture Volume = Paint Volume + Thinner Volume
Thinner % = [Thinner Parts ÷ (Paint Parts + Thinner Parts)] × 100
Volume Increase Factor = Total Mixture Volume ÷ Paint Volume
Total Cost = (Paint Volume × Paint Cost/L) + (Thinner Volume × Thinner Cost/L)
Cost per Liter = Total Cost ÷ Total Mixture Volume
Assumptions & References
- The ratio is expressed as Paint Parts : Thinner Parts (e.g., 3:1 means 3 parts paint to 1 part thinner).
- Volumes are assumed to be additive (no volume contraction on mixing), which is standard for paint/thinner systems.
- Common ratios: Latex/water-based paints typically use 10–15% water (≈ 7:1 to 6:1); oil-based paints use 10–25% mineral spirits (≈ 4:1 to 3:1); lacquers use 25–50% lacquer thinner (≈ 3:1 to 1:1).
- Always consult the manufacturer's data sheet (TDS) for the recommended thinning ratio for your specific product.
- Over-thinning reduces film build, adhesion, and coverage; under-thinning causes application issues such as brush drag and orange peel.
- Reference: ASTM D1475 (Standard Test Method for Density of Liquid Coatings) and manufacturer Technical Data Sheets (TDS).