Toys, Sporting Goods & Recreational Products calculator
Foam/plastic Material Usage Calculator
Work out how much foam or plastic to buy once molding or dispensing losses are counted. Enter the run, the material per part and your yield to see the purchase quantity.
What this calculator does
- Material to buy for a foam or plastic run, the theoretical need, and the loss allowance from yield.
Formula used
- Theoretical material = parts in the run × foam or plastic per part
- Material to buy = theoretical material ÷ (yield efficiency ÷ 100)
- Loss allowance = material to buy − theoretical material
- Material per part = material to buy ÷ parts in the run
Inputs explained
- Parts in the Production Run: Parts in the run, from the work order or build schedule.
- Foam or Plastic per Part: Pounds of foam or plastic each finished part consumes.
- Molding or Dispensing Yield: Share of material that ends up in good parts, in percent.
How to use the result
- Best suited to sizing a resin purchase order, comparing yield between two molding cells, checking material cost per part.
- One blended figure per part hides parts with very different shot weights or dispense volumes. It prices material only; regrind credit, purging and color change losses are separate.
Common questions
- Why does the buy quantity rise when yield falls? Material to buy is theoretical need divided by yield efficiency. At 85 percent you buy about 1.18 pounds for every pound the good parts need, and the extra covers process losses.
- Should the per-part figure be pounds? Yes on this page. The unit is fixed at pounds per part so the buy quantity lands in pounds. Weigh or estimate how much foam or plastic each part consumes.
- Does yield efficiency include rejected parts? No. It covers material the molding or dispensing process consumes, such as sprue, flash and purging. Parts rejected at inspection are a separate loss and are not in this figure.
- How do I convert a shot weight in grams? Multiply the shot weight in grams by 0.002205 to get pounds, then divide by the parts per shot. Enter the result as pounds per part.
Last reviewed 2026-10-01.