Calculate the hardener weight, phr, total batch mass, and optional material used cost from your resin EEW, hardener AHEW, and resin charge.
Table of contents
How to use our Epoxy EEW, Amine Ratio, Batch and Cost Calculator
- Copy the resin epoxy equivalent weight, EEW (g/eq), and hardener amine hydrogen equivalent weight, AHEW (g/eq), from the component technical data sheets.
- Enter the Resin mass to charge (g), meaning the resin-only amount you plan to weigh before adding hardener.
- Open Advanced options and keep Target amine-to-epoxy equivalent ratio at 1.00 unless a formulation instruction gives a different ratio.
- Enter both Resin price ($ per kg) and Hardener price ($ per kg) only if you want material used cost; otherwise leave both blank.
- Click Calculate, then confirm that the Hardener mass to add and Total mixed batch mass fit your scale capacity and planned batch size before mixing.
Definitions
EEW (epoxy equivalent weight): Grams of resin containing one epoxy equivalent. The calculator uses Resin epoxy equivalent weight, EEW (g/eq) to find the amount of epoxy-reactive material in the resin charge. [1]
AHEW (amine hydrogen equivalent weight): Grams of hardener that provide one reactive amine-hydrogen equivalent.
Equivalent ratio: Amine-hydrogen equivalents divided by epoxy equivalents. A Target amine-to-epoxy equivalent ratio of 1.00 is the stoichiometric starting point.
phr: Parts of hardener per 100 parts of resin by weight.
Material used cost: The proportional cost of resin and hardener consumed in this batch, not the cost of buying whole containers.
Common mistakes and quick fixes
Mistake: Using a package mix ratio in place of Resin epoxy equivalent weight, EEW (g/eq) or Hardener amine hydrogen equivalent weight, AHEW (g/eq).
Fix: Enter the EEW and AHEW values from the technical data sheets. Follow a product's stated formulated mixing ratio if it conflicts with this calculation.
Mistake: Entering final desired batch weight as Resin mass to charge (g).
Fix: Enter only the resin amount. The Total mixed batch mass adds the calculated hardener.
Mistake: Treating Hardener parts per 100 resin parts by weight as a volume ratio.
Fix: Weigh the Hardener mass to add. Do not measure this recipe by cups, milliliters, or pump strokes.
Mistake: Supplying Resin price ($ per kg) but leaving Hardener price ($ per kg) blank.
Fix: Enter both component prices for Batch material used cost, or leave both price fields blank.
Mistake: Typing 1,01 in Resin mass to charge (g) when you mean one point zero one grams.
Fix: Use a decimal point for decimals, such as 1.01. Use commas only for thousands, such as 1,000.5.
Limitations & Key Assumptions / Boundary Conditions
- This is a by-weight calculation. It does not create a volume ratio because density data is not included.
- Use a commercial product's technical data sheet or formulation instruction if it gives a specific mixing ratio. A raw EEW/AHEW calculation may not match a formulated product.
- The calculation assumes the entered EEW, AHEW, and target amine-to-epoxy equivalent ratio apply to the materials being mixed.
- Fillers, pigments, solvents, reactive diluents, accelerators, moisture, purity corrections, and process losses are not included.
- Batch material used cost excludes container-size rounding, shipping, hazmat fees, tax, handling, and other fixed charges.
- Use suitable scale accuracy and follow the product safety data sheet, cure schedule, ventilation, and handling instructions.
Methodology
Recipe calculation
The calculator first converts the equivalent weights into hardener parts per 100 resin parts by weight. A target equivalent ratio of 1.00 uses one amine-hydrogen equivalent for each epoxy equivalent. [2]
hardener phr = 100 x AHEW x target equivalent ratio / EEW
It scales that ratio using the resin-only charge, then adds the two component masses.
hardener mass (g) = resin mass (g) x hardener phr / 100
total mixed batch mass (g) = resin mass (g) + hardener mass (g)
The resin-to-hardener value is the same relationship written from the resin side.
resin parts per 1 hardener part = resin mass (g) / hardener mass (g)
Cost calculation
When both prices are entered, each component mass is converted from grams to kilograms using the exact conversion of 1,000 g per kg, then multiplied by its own price.
resin cost ($) = resin mass (g) / 1000 x resin price ($ per kg)
hardener cost ($) = hardener mass (g) / 1000 x hardener price ($ per kg)
batch material used cost ($) = resin cost ($) + hardener cost ($)
Mini-example
With EEW 190 g/eq, AHEW 60 g/eq, and a 1.00 target ratio, hardener phr is 31.5789. For a 1,000 g resin charge, the hardener mass is 315.789 g and the total mixed batch mass is 1,315.789 g. At $12 per kg resin and $18 per kg hardener, the proportional material used cost is $17.68.