The most common epoxy mixing ratios are 1:1 (equal parts) and 2:1 (two parts resin to one part hardener). However, ratios vary by product — some marine epoxies use 100:45, while certain industrial systems use 3:1, 4:1, or even 10:1. Always check your manufacturer's instructions for the correct ratio. Using the wrong ratio can result in incomplete curing, soft spots, or brittle results.

To calculate, divide your total amount by the sum of the ratio parts. For a 2:1 ratio (total 3 parts):
Part A = Total × (2 ÷ 3)
Part B = Total × (1 ÷ 3)

For example, 300 ml total at 2:1 gives 200 ml Part A and 100 ml Part B. Our calculator above does this instantly — just enter any value and the rest update automatically.

Yes! Mixing by weight (using a digital scale) is often more accurate than measuring by volume, especially for larger batches. Most epoxy systems have Part A and Part B with similar densities (around 1.0–1.2 g/cm³), so the volume ratio approximates the weight ratio. However, for maximum precision, check if your manufacturer provides a specific weight ratio, as density differences can shift the ratio slightly.

Incorrect mixing ratios lead to:
• Too much hardener (Part B): Rapid curing, excessive heat, brittleness, and potential yellowing.
• Too little hardener: Incomplete curing, sticky/soft surface, weak structural integrity.
• Poor mixing: Unmixed streaks cause soft spots that never fully cure.

Always measure precisely and mix thoroughly (typically 3–5 minutes), scraping the sides and bottom of your container.

Estimate your total volume first:
• Coating/Sealing: Area (sq ft) × coating thickness (inches) × 1.6 ≈ total ounces needed
• River Table/Casting: Length × Width × Depth (all in inches) ÷ 61 ≈ total gallons
• Filling cracks: Crack volume + 15% extra for waste

Once you have the total, use our calculator to split it into Part A and Part B based on your mixing ratio.

1:1 epoxies are generally easier to use (equal parts, less room for error), cure faster, and are common in general-purpose and craft applications. 2:1 epoxies typically offer stronger bonds, better chemical resistance, and are preferred for structural applications, boat building, and professional woodworking. The ratio is determined by the chemical formulation — never substitute one ratio for another thinking they're interchangeable.

Always measure and mix Part A and Part B first to the correct ratio, then add colorants, pigments, or additives. Adding pigments before mixing can throw off your ratio measurements. Most pigments and dyes are formulated to be added at 1–5% of the total mixed volume and won't significantly affect the cure if added after proper mixing.