Insulated Bag or Polystyrene Box: Which Fits Your Shipment?

An insulated bag and a polystyrene box do the same job, but in a different way. The choice depends on three things: how long your route takes, how much storage space you have, and how much handling the shipment gets.

Where the bag wins

Storage space is the strongest argument. Bags are delivered flat and take up a fraction of the space that boxes do. If you have a small warehouse, bags let you keep a multiple of the shipping capacity in stock.

On top of that, the unit price is lower and the weight is less, which feeds directly into your rate with parcel shipping.

Where the box wins

Cooling duration and sturdiness. A thick-walled polystyrene box holds temperature considerably longer than even a 6-layer bag, and it protects against impact and pressure. With a lot of handling or stacking, that's decisive.

The tipping point

Rule of thumb: up to about 24 to 48 hours without much handling, a bag is enough. Beyond that, or for shipments that pass through multiple hands, choose the box.

Often both

Many shippers use the bag inside a cardboard box. The box provides sturdiness and a tidy shipping appearance, the bag provides the insulation. That's cheaper than polystyrene and sturdier than a bag alone.

Do the math

Take your annual volume, the price per unit and the storage space you need. At large volumes, the difference in warehouse space can outweigh the difference in unit price.

Compare the range of polystyrene boxes and insulated bags side by side.