How many gel packs do you need per shipment? The calculation method

Short answer: for a standard chilled shipment (24–48 hours, box up to 20 litres), one 400-gram gel pack per 5–8 litres of contents is a good starting point. For frozen goods, double that; in summer temperatures, add one extra. Below is the full calculation method, based on our own test data.

What does the number of gel packs depend on?

Four factors determine how much cooling capacity you need: the transit time (12, 24, 48 or 72 hours), the target temperature (chilled below 8 °C or frozen below 0 °C), the outside temperature (winter or high summer) and the insulation value of the packaging. The last one is often underestimated: a gel pack in a plain cardboard box warms up within a few hours, while the same pack in a well-insulated box lasts 48 hours.

The test baseline: 400 grams in a thick-walled EPS box

Our reference point: one 400-gram gel pack in a thick-walled polystyrene box at a constant 25 °C ambient temperature keeps the contents below 0 °C for about 30 hours and below 8 °C for up to 48 hours. That is the maximum a single pack delivers; all rules of thumb below are derived from it.

Rules of thumb per situation

• Chilled, next-day (24 hours): 1× 400 g per 5–8 litres of box contents in insulated packaging.
• Chilled, 48 hours: 2× 400 g for boxes up to 20 litres; when in doubt, choose one heavier pack (600–1,000 g) over two light ones.
• Frozen goods: double the number compared to chilled and always use thick-walled insulation — frozen shipping in thin packaging cannot be done reliably with any number of packs.
• Summer (30 °C+ outside): add one extra pack per shipment and fill empty space — stagnant warm air is the biggest enemy.
• Flat products (fish fillets, sushi, charcuterie): use ice pack sheets instead of thick packs — they spread the cold evenly across the surface.

How to position the packs correctly

Always place gel packs on top of the products: cold air sinks and cools the whole box. For tall boxes, a combination works (bottom and top). Fill empty space with padding and make sure the products themselves are at the right starting temperature — a gel pack keeps things cold, it does not chill warm products down.

Packaging decides half the outcome

The same number of packs performs dramatically differently per packaging type. From light to heavy: an insulated bag inside a cardboard box (24–48 hours), a thin-walled EPS box (24–48 hours), a thick-walled EPS box (48–72 hours). Unsure about the combination? Request a sample or let our specialists calculate your route with you.

Measure once, always certain

Every chain is different. Put a data logger in the box on your next shipment and read out the temperature curve after arrival. Then you know exactly how much margin you have — and you often save packs (and shipping weight) on routes that turn out shorter than expected.