Resin Material Waste Calculator

Work out how much extra resin to mix for a waste percentage, what the waste costs, and the size of mixing cup you need.

Every pour loses resin: some stays in the cup, some runs down the side of the mould, some is left on the stirrer and some is simply the difference between the batch you made and the batch you needed. This calculator turns a waste percentage into millilitres, grams and money, and works out the size of mixing cup the batch actually needs. It is a planning and costing tool only.

At a glance

What you enter: Resin the project needs, Waste allowance, Resin density, Resin price per millilitre, Cup fill you work to
What you get: Extra resin to mix, Total mixed volume, Total mixed weight, Cost of the waste, Total resin cost, Mixing cup capacity needed, Mixing cup capacity needed
Formula shown: Yes, every step, right below your results.
Cost and privacy: Free, no account needed, and nothing you type is stored.

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Resin the project needs ml

The volume that actually reaches the mould, before any waste.

Waste allowance %

Resin left in the cup, on the stirrer and spilled. A 10 to 15 percent allowance is normal.

Resin density g/ml

About 1.05 to 1.2 grams per millilitre for most epoxy products.

Resin price per millilitre USD/ml

Divide the kit price by the mixed volume of the kit.

Cup fill you work to %

How full you are willing to fill a mixing cup. Seventy to eighty percent leaves room to stir without spilling.

Reset

Results are estimates for general information only, always verify with a professional or official source before acting on them.

How to use the Resin Material Waste Calculator

1 Enter Resin the project needs (ml), The volume that actually reaches the mould, before any waste.
2 Enter Waste allowance (%), Resin left in the cup, on the stirrer and spilled. A 10 to 15 percent allowance is normal.
3 Enter Resin density (g/ml), About 1.05 to 1.2 grams per millilitre for most epoxy products.
4 Enter Resin price per millilitre (USD/ml), Divide the kit price by the mixed volume of the kit.
5 Enter Cup fill you work to (%), How full you are willing to fill a mixing cup. Seventy to eighty percent leaves room to stir without spilling.
6 Press Calculate. You get Extra resin to mix, Total mixed volume, Total mixed weight, Cost of the waste, Total resin cost, Mixing cup capacity needed, Mixing cup capacity needed, and every intermediate step stays visible under "How is this calculated?"
7 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.

Worked examples

Real numbers run through this calculator. Open any example to load it into the form above and change it.

Half litre project at 12 percent waste

A project needing 500 ml, with a 12 percent allowance, resin at 0.035 per millilitre and a cup filled to 75 percent.

You enter

Resin the project needs: 500 ml
Waste allowance: 12%
Resin density: 1.10 g/ml
Resin price per millilitre: $0.04
Cup fill you work to: 75%

You get

Extra resin to mix: 60.00 ml
Total mixed volume: 560.00 ml
Total mixed weight: 616.00 g
Cost of the waste: $2.10
Total resin cost: $19.60
Mixing cup capacity needed: 746.67 ml
Mixing cup capacity needed: 25.25 fl oz

560 millilitres to mix, about 616 grams, of which about 2.10 is waste. Use a cup of at least 750 millilitres.

Open this example in the calculator →

Small 60 ml pour with heavy waste

A small pour where the loss to the cup is a large proportion of the batch.

You enter

Resin the project needs: 60 ml
Waste allowance: 25%
Resin density: 1.10 g/ml
Resin price per millilitre: $0.05
Cup fill you work to: 70%

You get

Extra resin to mix: 15.00 ml
Total mixed volume: 75.00 ml
Total mixed weight: 82.50 g
Cost of the waste: $0.75
Total resin cost: $3.75
Mixing cup capacity needed: 107.14 ml
Mixing cup capacity needed: 3.62 fl oz

75 millilitres to mix and a cup of at least 108 millilitres. A small graduated cup is more accurate than a big one here.

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Frequently asked questions

How much extra resin should I mix?

Ten to fifteen percent above the volume the mould needs is the usual allowance. A project needing 500 millilitres takes about 560 millilitres mixed. Below ten percent you risk running short, and a second batch mixed later may not match the first in colour or in cure. Above twenty percent you are paying for resin that will set in the cup.

What size mixing cup do I need?

One that holds the whole batch with room to spare. A 560 millilitre batch wants a cup of at least 750 millilitres if you work to about 75 percent of its capacity, because a cup filled to the brim cannot be stirred without spilling. Graduated cups are worth the small extra cost, since guessing a volume in an unmarked container is where short pours come from.

How much does the wasted resin cost?

Multiply the extra volume by your price per millilitre. On a 500 millilitre project at 0.035 dollars a millilitre, a 12 percent allowance costs about 2.10. It sounds small until you multiply it by every pour in a year. Weighing your cup empty and again after a pour is the cheapest way to find out what your real waste percentage is.

Can I reduce the waste instead of allowing for it?

Partly. Scraping the cup, using a silicone spatula and letting the cup drain into the mould for a minute all recover a little. Some waste is unavoidable because the resin that wets the walls cannot be poured. Be careful about leaving a mixed batch sitting while you scrape, because pot life is set by the product and the technical data sheet, not by the tool, and it varies enormously between products.

Should the waste percentage be based on the resin or on the mixed batch?

This tool bases it on the resin the project needs, which is the volume that reaches the mould. A 12 percent allowance on 500 millilitres is 60 millilitres, which is 10.7 percent of the 560 millilitre batch. Other tools quote waste against the batch instead, which is why the same percentage can appear to give slightly different answers.

Terms used here

Short, plain-language definitions of the words this calculator uses.

Degassing Removing bubbles from mixed resin, either by leaving it to stand so bubbles rise, by warming it to lower its viscosity, or with a vacuum chamber.Slow stirring and a warm room... Pot life The working time a mixed two-part resin remains pourable before it starts to thicken and set. Waste allowance The extra material bought on top of the calculated requirement, to cover cutting mistakes, defects, pattern matching, dye lot differences and simple bad luck.Typical allowances...

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