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Volumetric weight calculator

A free volumetric weight calculator online - enter your parcel dimensions and your carrier's divisor, and see whether you are billed on what it weighs or on the space it takes up.

What the parcel weighs on the scales.

Take this from your carrier's current service guide - it differs by carrier and by units.

Enter the parcel's dimensions and your carrier's divisor to see the billable weight.

How this is calculated

Volumetric weight = (Length × Width × Height) ÷ divisor
Chargeable weight = the greater of volumetric weight and actual weight

The divisor depends on your carrier AND on your units.
A cm/kg divisor and an in/lb divisor are not interchangeable.

Assumptions

  • The divisor is yours to supply. Courier divisors differ between carriers, between services within one carrier, and between metric and imperial paperwork - and they get revised. Take the current figure from your carrier's own service guide rather than from any calculator, including this one.
  • The default divisor shown is a starting point only and has not been verified against any carrier's published rate card. Overwrite it.
  • Dimensions are the outside measurements of the packed parcel. Most carriers round each dimension up before applying the divisor; this calculator does not, so treat the result as a floor rather than a ceiling.
  • Surcharges, fuel, remote-area fees and dimensional minimums are not included. This is the billable weight, not the price.

How to use this volumetric weight calculator

Enter the length, width and height of the packed parcel, the weight on your scales, and the divisor your carrier applies. The volumetric weight appears immediately alongside the actual weight, with the chargeable weight - the greater of the two - marked as the figure the invoice will be built on. There is no calculate button, and the arithmetic that produced the number is printed underneath so you can check it against a rate card line by line.

Everything runs in your browser. Nothing you type is sent to a server, and the numbers are written into the page address as you go, so copying the link hands a forwarder or a colleague the exact parcel you are looking at with every field already filled in.

Worked example

You are sending a box of pillows by courier. The packed carton measures 60 × 45 × 40 cm and it weighs 4.5 kg on the scales. Your carrier’s service guide gives a cm/kg divisor of 5000.

First the volume: 60 × 45 × 40 = 108,000 cm³.

Then the volumetric weight: 108,000 ÷ 5000 = 21.6 kg.

Compare that with the actual weight of 4.5 kg. The volumetric figure is nearly five times larger, so you are billed on 21.6 kg, not 4.5 kg.

That gap is the whole reason the concept exists. A carrier moving pillows is selling space, not lift, and a 4.5 kg charge would not cover the hold the box occupies.

Now run the same box with a divisor of 6000: 108,000 ÷ 6000 = 18 kg. Same parcel, same carrier weight, 3.6 kg less billable. Divisor choice is not a rounding detail - on a light bulky shipment it moves the invoice by twenty per cent.

Using this as a volumetric weight calculator for air freight

Air freight and express courier ask the same question and answer it with different numbers. Both convert a box into a billable weight by dividing volume by an assumed density, and both bill you on whichever of volumetric and actual weight is greater. What separates them is the divisor, and the gap is large enough that using a courier figure on an air waybill will give you a materially wrong quote.

Two more differences matter once you leave the parcel world. Air freight is quoted per kilogram of chargeable weight across a whole consignment rather than per piece, so a mixed pallet needs each piece calculated and then summed, not averaged. And the figure your forwarder files can be rounded up to a half or whole kilogram step depending on the airline’s tariff - a rounding you will see on the invoice and not here.

So run the same box twice: once on the divisor your courier quotes, once on your forwarder’s. That difference, multiplied by the rate, is what the routing decision is worth.

UPS, DHL, FedEx and the divisor question

The single most searched version of this question is some form of what divisor does my carrier use, usually with a carrier name attached. This tool deliberately does not answer that for you, and the reason is worth stating plainly rather than hiding behind a dropdown.

Divisors are commercial settings, not standards. They differ between carriers, between express and economy services at the same carrier, between domestic and international lanes, and between one country’s rate card and another’s for the same carrier and the same service. They also get revised, typically at an annual tariff update. Any calculator that hardcodes a number next to a carrier’s name is one tariff cycle away from being confidently wrong, and a wrong divisor does not look wrong - it produces a plausible number that is out by twenty per cent.

So the divisor is an input here. Find the current figure in the published tariff or rate guide for the exact service you are booking - every major integrator publishes one, and dimensional weight has its own section in all of them - and type it into the field. The calculator does the rest, and it will still be right next year.

Getting the divisor right

Beyond finding the number, there is one trap worth knowing about: units.

A divisor quoted for cm/kg is meaningless applied to inches and pounds. Substituting one for the other produces an answer wrong by roughly a factor of twenty-seven, because you have changed the length unit by 2.54 in all three dimensions while leaving the divisor alone. If your rate card is in imperial and your tape measure is in metric, convert the dimensions first and keep the metric divisor, or convert nothing and use the imperial divisor. Never mix.

The second trap is measuring the product rather than the parcel. Carriers measure what they have to fit on an aircraft, which means the outside of the packed box including any bulge, protruding lid, strap or handle.

What makes a real volumetric weight calculator

There are a lot of pages that will multiply three numbers and divide by 5000. What makes the result usable is everything around that division.

A real one shows actual and volumetric weight together, because the answer you need is which of them wins. It shows the working, so you can reconcile it against an invoice rather than trust it. It lets you change the divisor, the one variable that is genuinely yours to look up. And it is honest about what it leaves out - rounding, dimensional minimums, surcharges - so you read the number as a billable weight and not a price.

That is the standard this StowMath tool is built to: every assumption listed above the fold, the divisor left as a field you fill rather than a number presented as authoritative, and the full calculation on the page.

When volumetric weight will not bite

If your cargo is dense, the volumetric figure is irrelevant. A carton of ceramic tiles, fasteners, batteries or liquids will hit its actual weight well before the volume calculation catches up, and the carrier bills the scale reading.

The rough test is your parcel’s density in kilograms per cubic metre against the density the divisor implies. A cm/kg divisor of 5000 implies 200 kg per cubic metre. Cargo denser than that bills on actual weight; cargo lighter than that bills on volume. Knowing which side of the line you are on tells you whether shaving packaging is worth anything - for dense cargo it changes nothing at all.

Reducing the number

If volumetric weight is what you are paying on, the only lever is the box.

Right-sizing the carton is the obvious one, and the effect is cubic rather than linear: trimming each dimension by ten per cent removes about twenty-seven per cent of the volume. Removing dead air, using a carton that actually matches the product, and avoiding oversized void fill all pay off directly.

Splitting one large parcel into two smaller ones sometimes helps and sometimes does not - it depends on whether the carrier applies a per-parcel minimum charge, and on whether the split gets you under a dimensional surcharge threshold. Work out the chargeable weight both ways before assuming.

Frequently asked questions

What is volumetric weight?
Volumetric weight, also called dimensional or DIM weight, converts the space a parcel occupies into a weight figure so that a carrier can bill light bulky freight fairly. A box of cushions weighs almost nothing but fills an aircraft hold, so carriers charge on volume when volume is the binding constraint.
How is volumetric weight calculated?
Multiply length by width by height, then divide by your carrier's divisor. With a cm/kg divisor of 5000, a 40 × 30 × 20 cm parcel is 24,000 cm³ ÷ 5000 = 4.8 kg volumetric. If the parcel actually weighs 3 kg, you are billed on 4.8 kg.
How do I use a volumetric weight calculator?
Enter the three outside dimensions of the packed parcel, the weight on your scales, and the divisor printed in your carrier's service guide. The calculator returns the volumetric weight and the chargeable weight side by side, so you can see at a glance which of the two the invoice will be based on. Change the divisor and the answer updates immediately, which is the fastest way to see how much a carrier's dimensional setting is costing you.
Which weight will I actually be charged on?
The greater of the two, always. Carriers call this the chargeable weight. If your actual weight is higher the volumetric figure is ignored, and if the volumetric figure is higher your actual weight is ignored - you never pay on both and you never pay on the lower one.
Why do we divide by 5000 for volumetric weight?
A divisor is an assumed density written as a division. Dividing cubic centimetres by 5000 says that one cubic metre of space is worth 200 kg of revenue, because 1,000,000 cm³ ÷ 5000 = 200. Carriers pick that number commercially rather than physically, which is why 4000, 5000 and 6000 are all in circulation for cm/kg, and why 5000 is a common default rather than a universal rule.
What is 6000 in volumetric weight?
6000 is a cm/kg divisor that implies a density of about 166.7 kg per cubic metre, since 1,000,000 ÷ 6000 = 166.67. It is more generous to the shipper than 5000, because the same 108,000 cm³ carton comes out at 18 kg on a 6000 divisor and 21.6 kg on 5000. Which one applies to you is set by the service you booked, not by the size of the parcel.
How do I calculate volumetric weight in kg?
Measure in centimetres, multiply the three dimensions, and divide by a cm/kg divisor. A 60 × 45 × 40 cm carton is 108,000 cm³, and on a divisor of 5000 that is 21.6 kg volumetric. Keep the units consistent - an inches and pounds divisor applied to centimetres is wrong by a factor of roughly twenty-seven.
How do I convert volume to weight?
Physically, weight equals volume multiplied by density, so a 0.5 m³ crate of material at 300 kg per cubic metre weighs 150 kg. In freight you rarely know the true density, so carriers substitute an assumed one, which is exactly what the divisor is. That is why volumetric weight is a billing figure rather than a measurement, and why it can differ from what the scales say.
How do I calculate volume into kg?
For courier and air freight, divide the volume in cubic centimetres by the carrier's divisor - 108,000 cm³ on a 5000 divisor gives 21.6 kg. For LCL sea freight the convention is different. One cubic metre is counted as 1000 kg, and you are billed on whichever of volume or weight is greater. Both are commercial conventions, not physics.
What is 1 kg/m3?
One kilogram spread evenly through one cubic metre - an extremely low density. Fresh water is about 1000 kg/m³ and a cm/kg divisor of 5000 assumes 200 kg/m³, so 1 kg/m³ is a fraction of either. Nothing you ship by courier will be anywhere near it; the unit matters here mainly because it is what a divisor is really expressing.
What is 1% weight per volume?
1% w/v means one gram of substance in 100 millilitres of solution, which works out to 10 grams per litre or 10 kg per cubic metre. It is a concentration measure from chemistry and pharmacy rather than a freight term, so it will not appear on a courier rate card. If you arrived here looking for shipping arithmetic, the figure you want is the divisor, not a percentage.
Is volumetric weight the same as chargeable weight for air freight?
The arithmetic is the same shape but the divisor is not. Scheduled air freight uses a different volumetric standard from express courier, so the two produce different billable weights for the same box. Use the divisor your air freight forwarder quotes rather than the one on a courier rate card.
Does the carrier round my dimensions up?
Usually yes, and often to the next whole centimetre or inch before the divisor is applied. A 40.2 cm side may be billed as 41 cm. This calculator uses the figures exactly as you type them, so a real invoice can land slightly above what you see here.

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Sources & methodology

This calculator uses only definitional arithmetic - no carrier-specific or regulatory constants - so there is nothing external to cite.

Last updated

Results are estimates for planning purposes. Verify with your carrier or customs broker before committing. This is not professional advice - see the disclaimer.

Every calculation runs in your browser. Nothing you type is sent to a server or stored anywhere.