Dimensional weight and parcel size calculator
Enter a box’s size and weight to see its dimensional weight (also called volumetric weight) and billable weight at Canada Post, UniUni, Purolator, UPS and FedEx, and which of each carrier’s size limits it breaks.
Divisors and limits from each carrier’s published rules, checked . How we check
| Carrier | Dimensional | Billed as | Size limits |
|---|---|---|---|
| Canada Post | 9.3 lbRegular Parcel, divisor 166 | 9.3 lbSize sets the price | Fits |
| 11.1 lbOther services, divisor 139 | 11.1 lbSize sets the price | Fits | |
| UniUni | UniUni doesn’t publish its size limits or divisor. A quote asks UniUni directly and only shows it when it accepts the parcel. | ||
| Purolator | 11.1 lbGround, divisor 139 | 11.1 lbSize sets the price | Fits |
| 13.4 lbExpress, divisor 115 | 13.4 lbSize sets the price | Fits | |
| UPS | 11.1 lbStandard, divisor 139 | 11.1 lbSize sets the price | Fits |
| 13.4 lbExpress, divisor 115 | 13.4 lbSize sets the price | Fits | |
| FedEx | 11.1 lbGround, divisor 139 | 11.1 lbSize sets the price | Fits |
| 11.1 lbExpress, divisor 139 | 11.1 lbSize sets the price | Fits | |
- Canada Post Regular Parcel: fits
- Canada Post Other services: fits
- Purolator Ground: fits
- Purolator Express: fits
- UPS Standard: fits
- UPS Express: fits
- FedEx Ground: fits
- FedEx Express: fits
How to calculate dimensional weight
Short answer. Dimensional weight is a box’s length × width × height divided by the carrier’s divisor. In inches and pounds most Canadian services divide by 139 (5,000 in centimetres and kilograms); Canada Post Regular Parcel divides by 166 (6,000), and the air services of UPS and Purolator by 115. The carrier bills the higher of the actual weight and the dimensional weight.
- Measure the packed box’s length, width and height in inches, rounding each side up to the next whole inch.
- Multiply them for the volume in cubic inches.
- Divide by the carrier’s divisor and round up to the next pound. That’s the dimensional weight.
- Weigh the box. The billable weight is whichever is higher.
For example, a 20 × 16 × 12 inch box that weighs 8 lb is 3,840 cubic inches. Divided by 139 that’s 28 lb, so it bills at 28 lb rather than 8. Canada Post Regular Parcel, at 166, bills it at 24 lb, and a UPS air service, at 115, at 34 lb.
Dimensional weight divisors and size limits by carrier
| Carrier and services | Divisor, inches and pounds | Divisor, centimetres and kilograms | Heaviest | Longest side | Length + girth |
|---|---|---|---|---|---|
| Canada PostRegular Parcel | 166 | 6,000 | 66 lb | 78 in | 118 in |
| Canada PostOther services | 139 | 5,000 | 66 lb | 78 in | 118 in |
| UniUni | Not published. A quote asks UniUni directly and shows it only when it takes the parcel. | ||||
| PurolatorGround | 139 | about 5,000 | 70 lb | 108 in | 165 in |
| PurolatorExpress | 115 | about 4,150 | 70 lb | 96 in | 144 in |
| UPSStandard | 139 | 5,000 | 150 lb | 108 in | 165 in |
| UPSExpress | 115 | 4,100 | 150 lb | 108 in | 165 in |
| FedExGround | 139 | 5,000 | 150 lb | 108 in | 165 in |
| FedExExpress | 139 | 5,000 | 150 lb | 108 in | 130 in |
Dimensional weight vs actual weight
A big, light box takes up as much room on a truck as a big, heavy one, so carriers charge for space as well as weight. Actual weight is what the box weighs on a scale; dimensional weight is what its size would weigh at the carrier’s density. In inches and pounds the divisor is 115, 139 or 166, depending on the carrier and the service, and you’re billed for whichever weight is higher.
A smaller divisor makes the dimensional weight bigger. That’s why the same box can be billed at different weights by different carriers, and why the cheapest carrier for a light pillow can differ from the cheapest for a heavy book.
How to measure girth
Girth is the distance around the box at its thickest point: twice the width plus twice the height, with the longest side counted as the length. Carriers cap length plus girth, and a box over the cap is refused or charged as oversize. Some services have a lower cap than the carrier’s ground service: FedEx Express stops at 130 inches.
- Measure the longest side. That’s the length.
- Measure the other two sides, the width and the height, or wrap a tape measure once around the box at its thickest part.
- Girth is twice the width plus twice the height. Add the length for length plus girth.
The 20 × 16 × 12 inch box above has a girth of 56 inches (2 × 16 + 2 × 12), so its length plus girth is 76 inches, well inside every cap in the table. Long and flat boxes come closest to the caps: see our guides to shipping furniture and a painting.
How to measure a box for shipping
- Measure the outside of the box once it’s packed and taped. A bulging side counts.
- Round each side up to the next whole inch or centimetre, the way carriers do.
- Weigh the packed box with filler and labels, and round up.
- Save the boxes you use often, so the same box is entered the same way every time.
Our guide to how to measure a package has the full steps.
Carriers re-measure parcels at their depots. If their figures come out higher, they bill an adjustment. With ProtonShip, an adjustment is posted with the carrier’s reason, and its figures next to yours when it reports them, before anything is charged. How adjustments work
Questions about dimensional weight
Why divide by 5,000 for volumetric weight?
Because 5,000 cubic centimetres per kilogram is the density carriers price on: it treats a cubic metre as weighing 200 kg. A box less dense than that is billed by its size. In inches and pounds the same rule is about 139 cubic inches per pound, which is why Canadian carriers divide by 139.
How do I calculate dimensional weight for UPS?
Multiply the sides in inches, then divide by 139 for UPS Standard or 115 for UPS's air services: Expedited, Express Saver and Express. In centimetres and kilograms, divide by 5,000 or 4,100.
How does FedEx calculate dimensional weight?
FedEx rounds each side up to the next whole inch, multiplies them and divides by 139 (5,000 in centimetres), on every service within Canada.
Does Canada Post use dimensional weight?
Yes. Regular Parcel divides the volume in inches by 166 (6,000 in centimetres), and Expedited Parcel, Xpresspost and Priority by 139 (5,000).
How do you measure girth?
Measure the longest side of the box; that's the length. Girth is the distance around the box the other way: twice the width plus twice the height, or a tape measure wrapped once around the thickest part. Carriers cap length plus girth, so add the length to the girth to check a box against them.
What is billable or chargeable weight?
The weight a carrier charges for: the higher of the actual weight and the dimensional weight, rounded up. Air freight calls it chargeable weight. The calculator shows it for each carrier as "Billed as".
About these numbers
The calculator uses each carrier’s own divisors and size limits, service by service, as listed on our carriers page. Where a carrier’s services follow different rules, such as UPS billing its air services at 115, it shows each group. UniUni doesn’t publish its rules, so a quote checks UniUni parcels with UniUni directly. Carriers also round measurements and weights up before they bill, so a real label can come out slightly higher. A ProtonShip quote prices the box at each carrier and lists the services it fits. Common box sizes and what each bills at are in our shipping box sizes guide.
Compare four carriers in one quote
UniUni, Purolator, UPS and FedEx in one account, paid per label.