What this calculator does
Couriers don't always charge shipping by actual weight alone. A large, light parcel (like a lampshade or a box of pillows) takes up truck and plane space out of proportion to how much it weighs, so most couriers also calculate a "dimensional" (or volumetric) weight from the parcel's size, and bill on whichever of the two figures is higher.
This calculator works out that dimensional weight from length, width and height, and compares it against the actual weight entered to show which one a courier would charge on: the "chargeable weight". The divisor used varies by courier and service, so it's offered as an editable preset rather than a single fixed number.
The formula
Multiply length × width × height (in centimetres) and divide by the courier's divisor to get the dimensional weight in kilograms. The chargeable weight is whichever is larger: that figure, or the actual weight.
| Term | Meaning |
|---|---|
| Dimensional weight | A weight calculated from a parcel's volume rather than its actual mass, used by couriers to price large, light parcels fairly against the space they take up. |
| Divisor | The number a parcel's volume (in cm³) is divided by to get dimensional weight in kg. A smaller divisor produces a higher dimensional weight for the same size parcel. |
| Chargeable weight | Whichever is greater: the actual weight or the dimensional weight. This is the figure a courier actually bills against. |
The inputs explained
| Field | What to enter |
|---|---|
| Length (cm) | The parcel's length, in centimetres. |
| Width (cm) | The parcel's width, in centimetres. |
| Height (cm) | The parcel's height, in centimetres. |
| Actual weight (kg) | The parcel's actual weight, in kilograms, as it would read on a scale. |
| Courier divisor | The divisor the courier uses. This varies by courier and service type, so check the specific courier's published figure for an accurate result. |
When to use it
Checking a courier quote before shipping
A quote that seems higher than expected for a lightweight parcel is often because dimensional weight, not actual weight, was used to price it. This shows exactly why.
Choosing packaging size
A smaller box for the same contents can bring the dimensional weight below the actual weight, switching the chargeable weight back to the (often cheaper) actual figure.
Comparing two couriers' pricing
Different couriers publish different divisors; running the same parcel through each shows which is likely to work out cheaper for that specific size and weight combination.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How does chargeable weight change with parcel size, for a fixed 6 kg actual weight?
A parcel of fixed actual weight, with its dimensions scaled up.
| Length (width and height scale with it) | Dimensional weight | Chargeable weight |
|---|---|---|
| 30 cm | 4.50 kg | 6.00 kg |
| 40 cm | 6.00 kg | 6.00 kg |
| 50 cm | 7.50 kg | 7.50 kg |
| 60 cm | 9.00 kg | 9.00 kg |
Questions
Why do couriers use dimensional weight at all?
A courier vehicle or aircraft has a fixed amount of space, not just a weight limit. A large, light parcel uses up that space without contributing much actual weight, so dimensional weight lets couriers charge fairly for the space it occupies.
What divisor should I use?
It depends on the specific courier and service: commonly 5,000 for many international couriers, sometimes 4,000 for air freight or 6,000 for some domestic services. Check the courier's published rates for the figure that applies to a specific shipment.
Does reducing packaging size always help?
Only once dimensional weight is the larger figure. If actual weight is already higher than dimensional weight, shrinking the box further won't change the chargeable weight, since actual weight is already what's being charged.
Is this the same for international and domestic shipping?
The concept is the same, but the divisor used often differs between international and domestic services, and even between services from the same courier, so it's worth checking the specific service's published figure.
For a straightforward per-item shipping cost breakdown, see the shipping cost per unit calculator.