Quick answer: Volumetric weight is a parcel’s size converted into kilograms. Parcel networks multiply length by width by height in centimetres, divide by a set figure (usually 5,000) and charge whichever is higher: that number or the real weight. A dedicated van is priced differently, by vehicle, distance and urgency, so the sum doesn’t apply.
Six kilos of bedding, billed as nineteen. That’s volumetric weight at work, and if a parcel quote has ever jumped the moment you typed in the dimensions, it’s probably why. Here’s how couriers work it out, and how to stop it catching you out.
What Volumetric Weight Actually Measures
It’s a measure of space, not mass.
A parcel network makes its money by filling cages and vans. A big box of pillows takes up the same room as a big box of books, but it weighs a fraction as much. Charge on the scales alone and the pillows travel for almost nothing, while blocking space that paying freight could have used.
So the network puts a notional weight on the space your consignment takes up. You’ll see it called volumetric weight, dimensional weight or volume weight, and they’re all the same idea. Your real weight is then compared with it, and the higher figure becomes the chargeable weight. Space is worth real money right now: Ofcom says the UK sent and received a record 4.6 billion parcels last year, up 8.6% on the year before.
How to Calculate Volumetric Weight for a Courier
You need three measurements and one division.
Measure length, width and height in centimetres. Multiply them together. Divide by your carrier’s figure, which is most often 5,000 in the UK, and the answer is in kilograms. Here’s a 60 x 40 x 40cm carton, a common size for stock and office moves:
- 60 x 40 x 40 = 96,000 cubic centimetres
- 96,000 divided by 5,000 = 19.2kg volumetric weight
- Real weight 6kg: you’re charged for 19.2kg
- Real weight 25kg: you’re charged for 25kg
There’s a quicker test at your desk. At a divisor of 5,000, one cubic metre counts as 200kg. If your goods weigh less than 200kg per cubic metre, you’ll pay for space, not weight. Bedding, lampshades and foam packs nearly always land on that side. Books, tiles and machine parts usually don’t.
Why the Divisor Changes What You Pay
The divisor isn’t set by law.
Each carrier picks its own, and it can differ between services from the same firm. Most sit somewhere between 4,000 and 6,000. Run that same 96,000 cubic centimetre carton through each one and see what happens:
- Divide by 4,000: 24kg
- Divide by 5,000: 19.2kg
- Divide by 6,000: 16kg
That’s an 8kg swing on one carton before anyone’s opened a price list. A smaller divisor means a heavier chargeable weight, so a rate that looks cheap per kilo might not be. Some services only apply the rule once a parcel passes a set size or density, which is why the small print matters more than the headline. Comparing two quotes? Ask each one which divisor it uses. If you can’t find out, treat that as a warning.
How to Measure Without a Surprise Charge
Measure it packed, not bare.
Carriers can check parcels at collection or on the way through, then bill you the difference if your declared size comes up short. A few habits keep you clear of that:
- Take each measurement at the widest point, including any bulge, handle or strapping.
- Round up to the next whole centimetre.
- Treat a tube as a box: its length by its diameter by its diameter.
- Measure every piece on a multi-piece job, not just the biggest.
Then cut out the air. An oversized carton stuffed with void fill is where a lot of these charges come from. Trim that 60cm carton down to 50cm and it drops from 19.2kg to 16kg. Our guide on packing a parcel properly covers how much padding you really need, so you don’t swap a smaller box for a broken item.
What Sets the Price on a Dedicated Van
A van doesn’t care what the box weighs on paper.
On a dedicated van courier job the whole vehicle is yours, so there’s no shared space to ration. Your price comes from the vehicle, the distance and the urgency, roughly £1.10 to £1.80 per mile depending on those three, with guide prices from £39 for a Small Van. A carton of lampshades costs no more to carry than a carton of books.
We don’t ask for a volumetric weight when you ring. We ask about your biggest piece, how many pieces there are, the rough total weight and whether anything can go on top of anything else. A 60 x 40 x 40cm carton is about 0.1 cubic metres, so fifteen should fill our Small Van’s 1.5 cubic metres on paper. In practice we load ten to twelve, because boxes don’t stack as neatly as sums do.
Weight still counts, though. The right size of van has to carry your load legally, and a vehicle’s maximum authorised mass includes the most it can safely carry. Our Luton holds roughly 17.6 cubic metres but only around 1,000kg, so a van can run out of payload with space to spare.
When a Parcel Network Is Still the Better Deal
Sometimes it plainly is.
One carton, no deadline, nothing fragile: a network will usually beat a dedicated vehicle, and we’d tell you so. The sums start to tip when your job looks like one of these:
- Several bulky pieces are going to the same address. Each extra carton adds chargeable weight on a network, but nothing to a booked van that still has room.
- Your goods won’t enjoy being sorted through depots, like lampshades or display stands.
- It has to be there today.
Worth checking before you decide: what a same day courier costs for your distance, and how the cheapest same day options compare once the extras are added. Then you’re putting like against like.
What Online Sellers Must Show at Checkout
Selling bulky goods online? This bit’s yours.
The Competition and Markets Authority wrote to online retailers on 2 November 2026 about delivery fees. Where a customer has to pay for delivery to buy a product, the total price, including the minimum mandatory delivery charge, must be shown throughout the sale. Its summary is blunt: “The first price consumers see should be the price they pay.”
So if size drives your delivery fee, that fee can’t turn up as a shock at the last step. Work out the chargeable weight of your bulkiest products before you set the listing price, not after your first courier invoice lands. These rules protect consumers, so sales to other businesses sit outside them. Not sure how they apply to your shop? Read the CMA’s guidance or take advice.
At a Glance: Volumetric Weight
| Question | Short answer |
|---|---|
| What is it? | A parcel’s size converted to kilograms, so carriers can charge for the space it takes up. |
| What’s the usual formula? | Length x width x height in centimetres, divided by 5,000 on most UK services. |
| Which weight do I pay for? | Whichever is higher: the real weight or the volumetric weight. |
| What’s the quick test? | Goods under 200kg per cubic metre are charged on space at a divisor of 5,000. |
| Does a dedicated van use it? | No. Your price comes from the vehicle, distance and urgency, fixed in writing first. |
Frequently Asked Questions
Do couriers charge by weight or size?
Most parcel networks charge on both. They work out the real weight and a volumetric weight based on the parcel’s size, then bill whichever is higher. A light, bulky box ends up charged on size, and a small, dense one on weight. A dedicated van courier works differently: your price comes from the vehicle, the distance and the urgency.
How do you calculate volumetric weight for a courier?
Multiply the length, width and height in centimetres, then divide by your carrier’s figure, usually 5,000 in the UK. The result is in kilograms. A 50 x 40 x 30cm box comes to 60,000 cubic centimetres, which is 12kg at a divisor of 5,000. Measure the parcel once it’s fully packed, at its widest points.
Why is volumetric weight divided by 5000?
It’s an assumption about density. Dividing by 5,000 treats every 5,000 cubic centimetres as 1kg, which works out at 200kg per cubic metre. Carriers pick the figure to reflect what space in their network is worth. It isn’t set by law, and some services use 4,000 or 6,000 instead, so check the one your carrier applies.
Is volumetric weight the same as CBM?
No. CBM means cubic metres, which is a measure of volume. Volumetric weight turns that volume into kilograms so it can be priced like weight. At a divisor of 5,000, one CBM equals 200kg of volumetric weight, and half a CBM equals 100kg.
What is chargeable weight?
Chargeable weight is the figure your bill is based on. It’s the higher of two numbers: the real weight on the scales and the volumetric weight worked out from the dimensions. If a carton weighs 6kg but has a volumetric weight of 19.2kg, your chargeable weight is 19.2kg.
How can I reduce volumetric weight?
Use the smallest box that still protects the item. Cut tall cartons down, flat-pack anything that comes apart and swap loose void fill for fitted padding. Every centimetre counts: taking a 60 x 40 x 40cm carton down to 50 x 40 x 40cm drops it from 19.2kg to 16kg at a divisor of 5,000. Never cut protection just to save size.
Got bulky goods and a price that keeps climbing? Tell us what you’re moving, how big the largest piece is and where it’s going, and we’ll confirm a fixed, all-inclusive price in writing before a driver sets off.