Volumetric weight: what it is and how to calculate it

Quick answer: Volumetric weight (also called dimensional weight) is the "weight of the space" your parcel occupies. It is calculated like this: Volumetric weight (kg) = (length × width × height, in cm) ÷ conversion factor. Carriers always charge the higher of the two figures, actual weight on the scale or volumetric weight.

• Factor 5,000 on most international metric services: DHL, UPS, FedEx and DPD.
• Factor 139 on US domestic services from UPS and FedEx, where dimensions are in inches and weight in pounds.
• Colissimo applies volumetric weight only to air shipments, and exempts most of Western Europe.

What is volumetric weight?

Carriers move parcels in vans and aircraft with a fixed amount of space. A large, light box takes the place of several small, heavy ones, so charging on scale weight alone would never work.

To make pricing reflect reality, carriers use volumetric weight: a way of turning the size of a parcel into a billable "weight". They then compare it with the actual weight and charge whichever is higher. That figure is your chargeable weight.

The classic example: a set of cushions weighing 2 kg takes up far more room than a 2 kg toolbox. Same weight on the scale, very different cost to move.

How to calculate volumetric weight

The formula never changes. Only the conversion factor does:

Volumetric weight (kg) = (L × W × H in cm) ÷ factor

Worked example (using 5,000, the most common factor):

• A box measuring 40 × 30 × 20 cm, weighing 3 kg on the scale.
• Volume = 40 × 30 × 20 = 24,000 cm³.
• Volumetric weight = 24,000 ÷ 5,000 = 4.8 kg, usually rounded up to the next 0.5 kg = 5 kg.

So even though the scale says 3 kg, you are billed as if the parcel weighed 5 kg, because the volumetric figure is higher.

Conversion factors by carrier

Each carrier sets its own factor, and this is where most stores get caught out.

The Colissimo case is worth knowing if you ship from France. La Poste states that it applies volumetric weight to parcels sent by air, and explicitly exempts a long list of European destinations including Germany, Spain, Italy, the Netherlands, Belgium, Portugal and the United Kingdom. Domestic French parcels are billed on actual weight, within the standard size limits.

Sources: Colissimo, volumetric weight, plus the published rate guides from DHL, UPS, FedEx and DPD. Factors vary by service, by route and by contract, so check your own agreement.

When does volumetric weight hurt most?

Whenever you ship products that are light but bulky, in other words low density. The usual suspects in e-commerce:

• Clothing and textiles: cushions, duvets, towels
• Electronics in large retail packaging
• Plastic goods, toys, homeware
• Anything shipped in a box that is too big for what is inside

In all of these, it is the volumetric weight, not the scale, that sets your invoice.

How to reduce volumetric weight and pay less

The good news: this is one of the easiest shipping costs to cut, and the effect is immediate.

• Use the tightest box you can. Every extra centimetre adds volume, and volume is money.
• Swap boxes for padded mailers on textiles. They collapse around the product and leave almost no empty space.
• Standardise on two or three pack sizes that cover most of your orders. It simplifies the packing bench and stops oversized boxes creeping in.
• Drop the unnecessary void fill, the extra paper and bubble wrap that inflate the box.
• Measure before you ship, so you can anticipate the chargeable weight instead of discovering it on the invoice.

These packaging decisions feed straight into your wider plan to reduce shipping costs, and they change which carrier comes out cheapest, which is exactly what a carrier comparison is for.

And if you would rather not do the maths

Fair enough. Let us be honest about one thing: the factor itself, the 5,000 and its cousins, is set by the carrier. Neither you nor we can change it. What actually costs you time is everything around it, multiplying box dimensions and remembering which carrier uses which number, shipment after shipment.

That is the part ParcelRush takes off your hands. From the dimensions and weight on the order, and the route between origin and destination, the platform applies each carrier's factor automatically, works out the chargeable weight, and shows you the real price from each of them. You pick the cheapest without doing a single calculation by hand.

👉 See what your next shipment actually costs. Try the platform →

Frequently asked questions

What is volumetric weight?

It is a weight derived from the size of your parcel rather than what the scale says. Carriers use it to charge for the space a parcel takes up, and they always bill the higher of the two figures, actual weight or volumetric weight.

How do you calculate volumetric weight?

Multiply length by width by height in centimetres, then divide by the carrier's conversion factor: volumetric weight (kg) = (L × W × H in cm) ÷ factor. The most common factor is 5,000.

What conversion factor does each carrier use?

On international metric services, DHL, UPS, FedEx and DPD typically use 5,000. UPS and FedEx switch to 139 on US domestic services measured in inches and pounds. Always check the carrier's own calculator, since factors change and can be negotiated in your contract.

Does volumetric weight always apply?

No. It only applies when it exceeds the actual weight of the parcel. Heavy, compact products are billed on actual weight; light, bulky ones are billed on volumetric weight.

How can I pay less?

Cut the empty space. Use the smallest box that still protects the product, switch to padded mailers for textiles, and drop the excess void fill. Every centimetre counts.