EPS or EPP: which box should you choose?

EPS and EPP are similar: both are foamed plastic, both insulating, both lightweight. Yet you choose them for different situations. The difference isn't in the insulation but in what happens to the box after the trip.

EPS: for single use

EPS boxes are styrofoam. Cheap, excellent insulation and lightweight. The structure is brittle: drop a box and a corner breaks off. For shipments that don't come back that's not a problem, and it's precisely the low unit price that makes EPS the standard choice for single-use shipping.

EPP: for return logistics

EPP is tougher. Where EPS breaks, EPP springs back. An EPP box lasts hundreds of trips without losing insulation. That comes with a significantly higher purchase price.

The calculation

Divide the price of an EPP box by the number of trips you expect, and compare that to the unit price of EPS. For fixed routes, deposit systems or internal logistics between locations, EPP almost always wins. For shipping to end customers who don't send anything back, EPS wins.

Insulation

In terms of insulation value there's little difference between them at equal wall thickness. So don't let that be the deciding factor; look at lifespan and whether the packaging comes back.

Weight and volume

At equal wall thickness, EPP is slightly heavier. For parcel shipping where you pay per kilo, that can matter. For your own transport it barely plays a role.

In practice

Shipping to consumers or one-off buyers: EPS. Running fixed routes or getting the packaging back: EPP. If you're unsure, calculate using your own return rate; that number decides.