EPS Density & Yield Calculator
Relate target foam density, foam volume and raw bead mass — plus yield per kilogram and expansion ratio — in one place.
Use this calculator to estimate how much raw EPS bead a job requires, the foam yield you get per kilogram of bead, and the expansion ratio between unexpanded and finished foam. It is aimed at EPS process engineers, pre-expansion operators and buyers planning a batch or quoting a job.
Results
- Raw bead mass needed
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- Foam yield (m³ per kg of beads)
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- Expansion ratio (bulk ÷ final density)
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Note: assumes finished foam mass ≈ raw bead mass; minor pentane / moisture loss is ignored.
How this is calculated
The calculator uses mass conservation — the mass of the finished foam is taken as equal to the mass of raw bead that went into it (density is simply mass divided by volume):
- Raw bead mass (kg) = density (kg/m³) × foam volume (m³)
- Yield (m³ per kg) = 1 ÷ density (kg/m³)
- Expansion ratio = unexpanded bulk density ÷ final foam density
Assumptions & limitations
- Finished foam mass is treated as equal to the raw bead mass; pentane blowing agent loss and moisture pick-up/loss are ignored. Real bead consumption is usually a few percent higher.
- The 600 kg/m³ unexpanded bulk density is a typical starting value only. Bulk density varies by grade and supplier — confirm the figure for your material.
- Density here means finished (apparent) foam density, not pre-expander first-pass density. Re-expansion stages will change the relationship.
- Results are planning estimates. Validate against your own production records before committing to a quote.
Related reading and equipment:
- EPS bead expansion (pre-expander) machinery — where density is set.
- EPS density guide — how density affects strength, insulation and cost.
- EPS block molding equipment — turning expanded bead into blocks.