How do you calculate a two-part adhesive mix ratio?

Divide the Part A resin amount by the Part B hardener amount, then multiply by any supplier conversion factor. With 100 of resin to 25 of hardener and a factor of 1, the ratio is 4, meaning 4:1 A to B.

What does a 4:1 mix ratio mean?

It means four parts of resin for every one part of hardener, by whatever basis - weight or volume - the datasheet specifies. The 100-to-25 example yields exactly this 4:1 proportion.

Why does the conversion factor matter?

Datasheets give ratios by weight or by volume, and the two differ because the components have different densities. The conversion factor rescales a raw measured ratio to the basis your pump or spec uses.

What happens if the mix ratio is wrong?

Off-ratio mixing leaves unreacted resin or hardener, producing a soft, tacky, or brittle bond with a fraction of rated strength. Even a 5-10% error can be enough to fail a structural joint.

Is mix ratio by weight the same as by volume?

No. Because resin and hardener densities differ, a by-weight ratio rarely equals the by-volume ratio. Always confirm which basis your datasheet uses and apply the conversion factor accordingly.

How do I verify my metering pump is on ratio?

Dispense each component separately into tared containers over a set time, weigh or measure them, and run the amounts through this calculator. Compare the result against the datasheet ratio and adjust the pump if it deviates.

Adhesives, Sealants & Industrial Bonding calculator

Two-Part Mix Ratio Calculator

The mix ratio is the proportion of Part A resin to Part B hardener that a two-component adhesive needs to cure to full strength. This calculator divides your resin amount by your hardener amount to give the A:B ratio, then applies a supplier conversion factor so you can switch between the by-weight and by-volume basis the datasheet specifies. Operators and process engineers use it to verify a metering pump setting or a hand-mix proportion before a structural bond goes down. An off-ratio mix - even by a few percent - leaves uncured resin or unreacted hardener and silently halves bond strength, so confirming the ratio is a basic but high-leverage check.

What this calculator does

Calculate the mix ratio between resin and hardener after applying the required supplier conversion factor.
a bonding technician needs to verify Part A to Part B ratio before a mixed adhesive batch is released
It computes the raw Part A to Part B ratio from your two amounts and then the adjusted ratio after applying the supplier conversion factor.

Formula used

Raw mix ratio = Part A resin amount ÷ Part B hardener amount
Adjusted mix ratio = raw mix ratio × supplier conversion factor

Inputs explained

Part A resin amount:
Part B hardener amount:
Supplier mix-ratio conversion factor:

How to use the result

Use it to verify a metering setup, convert a datasheet ratio between weight and volume, or sanity-check a hand-mix before bonding.
Mixed mass and volume ratios differ because resin and hardener have different densities, so use the conversion factor and never assume a by-weight ratio equals the by-volume ratio.

Current U.S. benchmarks

The producer price index for industrial chemicals stands at 344.336 (BLS, May 2026), up 16.1% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 11,391 plastics and rubber products establishments employing about 815,988 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate a two-part adhesive mix ratio? Divide the Part A resin amount by the Part B hardener amount, then multiply by any supplier conversion factor. With 100 of resin to 25 of hardener and a factor of 1, the ratio is 4, meaning 4:1 A to B.
What does a 4:1 mix ratio mean? It means four parts of resin for every one part of hardener, by whatever basis - weight or volume - the datasheet specifies. The 100-to-25 example yields exactly this 4:1 proportion.
Why does the conversion factor matter? Datasheets give ratios by weight or by volume, and the two differ because the components have different densities. The conversion factor rescales a raw measured ratio to the basis your pump or spec uses.
What happens if the mix ratio is wrong? Off-ratio mixing leaves unreacted resin or hardener, producing a soft, tacky, or brittle bond with a fraction of rated strength. Even a 5-10% error can be enough to fail a structural joint.
Is mix ratio by weight the same as by volume? No. Because resin and hardener densities differ, a by-weight ratio rarely equals the by-volume ratio. Always confirm which basis your datasheet uses and apply the conversion factor accordingly.

Last reviewed 2026-05-12.