Got a shipping quote higher than you expected for a light box? The reason is usually volumetric weight: an aircraft fills up on space before it fills up on weight, so the carrier charges you on the greater of what the scale reads and the volume your box takes up. Here is the full explanation, with the formula and examples, and how we reduce it for you free.
The formula
Volumetric weight in pounds = length × width × height in centimeters ÷ 2268 (the same as volume ÷ 5000 in kilograms). In inches: length × width × height ÷ 138, approximately. Then chargeable weight = the greater of actual and volumetric, rounded up to the next pound, and the price is built on that alone. Our calculator applies the same formula the carrier applies, so no figure surprises you after shipping.
Examples from real parcels
| Contents | Box dimensions | Actual weight | Volumetric weight | Chargeable | Economy |
|---|---|---|---|---|---|
| A pair of sneakers in the store’s carton | 14 × 9 × 5 inches | 2 lb | 630 ÷ 138 = 4.6 | 5 lb | $95 |
| The same shoes after repacking | 13 × 8 × 5 inches | 2 lb | 520 ÷ 138 = 3.8 | 4 lb | $80 |
| A 15-inch laptop in its box | 18 × 13 × 3 inches | 6 lb | 702 ÷ 138 = 5.1 | 6 lb | $101 |
| A Dyson vacuum in the store’s carton | 32 × 12 × 10 inches | 12 lb | 3840 ÷ 138 = 27.8 | 28 lb | $291 |
| Two pillows in a roomy carton | 24 × 18 × 12 inches | 4 lb | 5184 ÷ 138 = 37.6 | 38 lb | $359 |
Prices come from the calculator at the moment you read this. Note the pillows: 4 lb on the scale becomes 38 lb chargeable, because volume is what gets charged. And note the shoes: a simple repack took off a full pound.
How to measure your box before you buy
- On Amazon, look for Package Dimensions in the product details; these are the dimensions of the shipping box, not the product, and they are what gets charged.
- Measure the longest side first: a heavy or extra-long box gets a carrier fee, and the calculator warns you and suggests splitting.
- Enter the dimensions and weight in the calculator and it gives you the chargeable weight and the price before you buy; there is no need to work it out yourself.
Five ways to reduce volumetric weight
- Free repacking: we remove the stores’ outer cartons and the air pillows and put the product, in its original box, into a right-sized box. Request it from your account along with your shipping request.
- Consolidation: one full box costs less than three half-empty ones, because empty space is charged. The consolidation numbers.
- Shoes: ask us to keep the original box and remove the shipping carton; the difference is a pound or two per pair.
- Clothing: folded and compressed on request; ten pieces fit in a 12 × 10 × 8 inch box, which is about 7 lb volumetric.
- Large devices: the product’s original box is often much smaller than the store’s shipping carton; we discard the outer one and secure the original.
When does reducing it not help?
When the product itself is large and light (pillows, large children’s toys, lamps); here it is charged on its volume whatever we do, and the fix is to buy it together with small, heavy items that fill the same space, so you do not pay twice. As for a heavy or extra-long box, we split it across two boxes if that costs less than the carrier fee.
Take the box dimensions from the product page (Package Dimensions on Amazon, for example) and enter them with the weight in the calculator; it gives you the chargeable weight and the price at once. If you cannot find the dimensions, send us the link and we estimate them for you.
The store states the product’s weight, while we weigh the box with its contents and packaging and measure its dimensions after it arrives. What appears in your account after receipt is both the actual and the volumetric weight, and you can choose repacking before shipping.
Yes; the formula is the same for all three services, and they differ only in price and transit time.
Chargeable weight is rounded up to the next pound: 4.6 lb volumetric is charged as 5 lb. This is the international carriers’ standard, not a rule of our own.
Work out your chargeable weight before you buy
Enter the box dimensions and weight in the calculator and you will see the chargeable weight and the price before you order, and repacking with us is free.
