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. UPS uses 166 on its retail (counter) rates.
- 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, then rounded up according to the carrier's rule: to the next 0.5 kg at UPS, to the next whole kilogram at DPD. Either way, 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.
Run the numbers on your own boxes. The tool starts from this example, change the dimensions and the weight:
Conversion factors by carrier
Each carrier sets its own factor, and this is where most stores get caught out.
| Carrier | Conversion factor (cm³/kg) | When it applies |
|---|---|---|
| DHL | 5,000 (international, metric) | Whenever volumetric exceeds actual weight |
| UPS | 5,000 (international, metric) | Same, and on US domestic in inches and pounds: 139 on daily rates, 166 on retail rates |
| FedEx | 5,000 (international, metric) | Same, and 139 on US domestic |
| DPD | 5,000 (international and road) | Whenever volumetric exceeds actual weight |
| Colissimo | 5,000 | Air shipments to French Overseas territories and international destinations only, with most of Western Europe exempt |
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; DHL Express France, 2026 service and rate guide, page 15; DPD France, general terms and conditions of sale, January 2026, articles 3.3 and 7.1; UPS, shipping dimensions and weight, France and United States. 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.
- Do not count on less void fill. Volumetric weight is measured on the outside of the box: taking paper or bubble wrap out changes none of the three dimensions, so nothing on the invoice. Less padding only helps if it lets you move to a smaller box. The EU PPWR regulation points the same way, since it counts padding as empty space.
- 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. ParcelRush sends the order's dimensions, weight and destination to every carrier connected to your account, and each one returns its price, volumetric weight included, worked out with its own rule and your own rates. You see the prices side by side and pick the cheapest without doing a single calculation by hand. The factor itself is fixed, but which lanes the rule applies to is part of what you have confirmed when negotiating your rates.
👉 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, and UPS uses 166 on its retail rates. 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?
Shrink the box. Volumetric weight is worked out from its outside dimensions, so removing void fill changes nothing on the invoice: only a smaller box brings it down. Use the smallest box that still protects the product, and switch to padded mailers for textiles. Every centimetre counts.
And once you know the real cost, it drives another number: the order value from which you can offer free shipping without losing money.
Maëlle Lemarchand CEO of ParcelRush. 15 years in web, UI/UX and e-commerce. Writes about shipping, logistics, e-commerce and marketing. LinkedIn
