Volumetric weight in Europe: divisors per carrier 2026

A light product in a big box is the most common way to pay for air. Carriers price by the space a parcel takes in the van or plane, not only by what it weighs, and they do that with one number: the divisor. It differs per carrier and sometimes per country, which is why the same box can cost a different "weight" with two carriers.

This article lists the divisors that European carriers publish themselves, works through one box with all of them, and shows how the four parcel formats on AirPost are sized against them.

How do you calculate volumetric weight? #

1. Measure the box in centimetres at its longest points: length, width, height. Round each to a whole centimetre (UPS asks for the nearest whole number).
2. Multiply the three. That is the volume in cubic centimetres.
3. Divide by the carrier’s divisor. The result is the volumetric weight in kilograms.
4. Compare it with the real weight, packaging included. The higher of the two is the billable weight.

Some carriers publish a density instead of a divisor — kilograms per cubic metre. They are the same thing: divide 1,000,000 by the density to get the divisor. 200 kg/m³ is a divisor of 5,000; 250 kg/m³ is 4,000; 167 kg/m³ is about 6,000.

Which divisor does each carrier use? #

Two things follow from the table. First, 5,000 is the common number for express and international networks, but it is not universal — the national parcel networks in Spain and Italy use both lower and higher divisors. Second, a lower divisor is stricter: at 3,333 the same box counts half again as heavy as at 5,000.

A worked example: one box, five carriers #

Take a pair of shoes in a 40 × 30 × 20 cm box that weighs 2 kg on the scale. The volume is 40 × 30 × 20 = 24,000 cm³.

The 2 kg pair of shoes is billed as 4 to 7.2 kg depending on who carries it. A smaller box does more than any carrier choice: the 35 × 25 × 15 cm box brings it down to 2.6 kg at a divisor of 5,000, against 4.8 kg for the bigger box at the same divisor.

• ✓Measure the packed box, not the product. Bulging sides count.
• ✓Keep a few box sizes and use the smallest that fits. Void fill is cheaper than a size up.
• ✓Soft goods (clothing, textiles) go in a padded envelope or mailer bag: almost no volume, so the real weight counts.
• ✕One large box size for everything "to keep it simple". Every light order then pays for air.
• ✕Rounding down. UPS rounds each side to the nearest centimetre and the result up to the next half kilogram.

How the AirPost parcel formats work #

On AirPost you do not enter box sizes per order. There are four formats, each with one box and one weight limit, and every price on the rate card was quoted with that box. Here are the four, with what each box counts as at the divisors above:

At 5,000 and 6,000 each box counts as less than its own weight limit, so a parcel that fits the box and stays under the limit is priced on its real weight. At 4,000 the medium box (11.8 kg) goes over its 10 kg limit and the large box reaches 30 kg, which is why the formats matter most with the stricter national networks.

• Each format has a weight range. Small up to 5 kg, medium up to 10 kg, large from 10 to 30 kg; letterbox up to 2 kg, and only with a service that delivers through the letterbox. The weight includes packaging.
• The price covers the format box. Every label is quoted and bought with that box, so pack to fit it. A parcel bigger than its format box falls under the carrier’s own rule in the table above.
• Weight points, not bands. Prices are measured at 2, 5, 10 and 30 kg, and your parcel is priced at the lowest point that carries it — a 1.8 kg parcel at the 2 kg price, not the 5 kg one.
• The medium box fits lockers. 45 × 35 × 30 cm was chosen because it fits every parcel locker in our data (InPost, ORLEN, Posti, Omniva, LP Express, Matkahuolto), so a locker service is not ruled out by the medium box.
• Some services are stricter. A letterbox slot or a smaller locker compartment can be tighter than the format box; where that is the case, the service shows its own maximum size.

The AirPost price is the carrier rate plus our €0.85 platform fee per parcel; the fee you agree with your sender comes on top. For the carrier rates alone at each weight point in every country, see the European shipping rates index; for the wider picture, parcel shipping costs in Europe. Whether a small parcel should go to a point or the door is covered in pickup point vs home delivery, and when a cheaper untracked letter is enough in tracked vs untracked shipping.

With local fulfilment through AirPost, a verified person near your customer packs each order into the format box and ships it as a domestic parcel. Send your stock in the packaging you want used, and the format does the rest.