Resin Mixing Ratio Calculator

How Resin Mixing Ratios Work

Epoxy resin and hardener must be mixed in the exact ratio specified by the manufacturer. This ratio is typically expressed as Part A : Part B — for example, 2:1 means two parts resin to one part hardener. Getting this ratio wrong can result in a sticky, uncured, or brittle finish. Our resin mixing ratio calculator removes the guesswork, giving you precise measurements every time.

Weight vs Volume Ratios

Most epoxy systems specify a ratio by weight rather than volume, because weight measurements are more accurate and repeatable. Volume ratios can be affected by temperature, viscosity, and how tightly the resin settles. If your product lists a weight ratio, always use a digital scale. If it lists a volume ratio, use graduated mixing cups. Our calculator supports both modes so you can work the way your product requires.

Scaling Batches Safely

When scaling up — say from 100g to 500g — the ratio must remain identical. Multiply both Part A and Part B by the same factor. Our batch scaling feature does this automatically, showing you total quantities for multiple identical batches. Never estimate; small errors multiply quickly.

Measurement Accuracy & Common Mistakes

• Using volume when the spec says weight — this is the #1 cause of uncured resin.
• Eyeballing "close enough" — a 10% error can ruin a batch.
• Not zeroing the scale — always tare your mixing container first.
• Mixing too little — scrape the sides and bottom of the cup thoroughly.
• Ignoring temperature — cold resin is thicker and harder to mix accurately.

Always Follow the Technical Data Sheet

This calculator is a helper — not a replacement for your manufacturer's instructions. Different epoxy brands use different ratios, pot lives, and cure times. Always read the technical data sheet (TDS) or safety data sheet (SDS) that came with your resin. When in doubt, mix a small test batch first.