Choosing an insulated box for shipping: EPS, EPP, foldable thermal box or insulated bag?
An insulated box keeps your product at temperature during transport, but not every insulated box does so in the same way. Wall thickness, material, storage and price differ greatly. In this overview we set the four common types side by side: the EPS box, the EPP box, the foldable thermal box and the insulated bag. That way you can choose the right box for your shipment in a few minutes.
The four types at a glance
| Type | Cooling time (indicative) | Storage | Best for |
|---|---|---|---|
| EPS box | 24 to 48 hours | Bulky | Parcel shipping of food and pharma |
| EPP box | 24 to 48 hours, reusable hundreds of times | Bulky | Fixed routes with returns |
| Foldable thermal box (4 or 6-layer) | 48 to 72 hours | Flat, up to 5x more per pallet | Webshops, peaks, little storage |
| Insulated bag | 12 to 24 hours | Flat | Small and flat shipments |
Cooling time always depends on the amount of coolant, the outside temperature and how full the box is. The figures above assume a well-filled box with enough gel packs.
EPS box: the standard
The EPS box (polystyrene) is the most widely used insulated box for chilled shipping. EPS consists of 98% trapped air and therefore insulates well at a low weight. Wall thickness determines performance: thin-walled boxes (around 15 to 20 mm) are light and economical for short transits; thick-walled boxes (30 to 50 mm) stay below 0 °C for around 30 hours and below 8 °C for up to 48 hours at an outside temperature of 25 °C. An EPS box has a matching lid, does not absorb moisture and is available with and without drain holes.
Drawback: an empty EPS box is mostly air, so you store a lot of volume. If you ship hundreds of boxes a week, that matters.
EPP box: reusable and sturdy
An EPP box looks like EPS, but is tough and resilient. It does not break when dropped and can be used hundreds of times. That makes EPP the logical insulated box for fixed routes where the boxes come back: catering, deliveries between branches, laboratories. More expensive per unit than EPS, but cheaper per trip. More on this in EPS or EPP: which box should you choose?
Foldable thermal box: saves space
A foldable thermal box consists of a cardboard outer box with a separate insulated liner bag of 4 or 6 layers. Everything is delivered flat, so up to 5 times as many fit on a pallet as with EPS. The 4-layer version is sufficient for up to around 48 hours chilled; the 6-layer version reaches 48 to 72 hours and is suitable for frozen goods and longer routes. The outer box can be printed and looks like an ordinary parcel. Also compare Foldable thermal box or EPS box.
Insulated bag: light and economical
An insulated bag goes into a standard shipping box or envelope. It is the cheapest insulation per shipment and takes up hardly any space. Suitable for small quantities that are delivered within a day, such as medicines, samples or a single meal.
And for very large volumes?
For very large numbers of boxes per year, a cardboard honeycomb box is an option, including made to measure. We supply these by quotation only; please contact your account manager.
How to choose in three questions
- How long is the shipment in transit? Up to 24 hours: insulated bag or thin-walled EPS. Up to 48 hours: thick-walled EPS or 4-layer foldable thermal box. Up to 72 hours or frozen: 6-layer foldable thermal box or thick-walled EPS with extra cooling.
- Does the box come back? Yes: EPP. No: EPS, foldable thermal box or insulated bag.
- How much storage do you have? Little space or big peaks: foldable thermal box. Plenty of space and lowest unit price: EPS.
Do not forget the coolant
An insulated box does not cool by itself. Allow 400 grams of gel pack per 5 litres of volume for 24 hours chilled, and double that for 48 hours or frozen. For reusable routes, rigid cooling elements are more practical.
Frequently asked questions
Which insulated box stays cold the longest?
A foldable thermal box with a 6-layer insulated bag or a thick-walled EPS box, both with enough coolant. That gets you 48 to 72 hours.
Is a lid on an insulated box necessary?
Yes. An EPS or EPP box without a properly fitting lid loses a lot of cold through the seam. Tape the lid shut all the way round.
Can I reuse an insulated box?
EPP is made for reuse. EPS and the insulated bag of a foldable thermal box can be used a few times as long as they are undamaged.
How quickly is it delivered?
All standard sizes are in stock, from our own production since 1972. Ordered before 14:00, shipped the same day.
