What is a dimensional weight calculator?

A dimensional weight calculator turns a parcel's length, width, and height into volumetric weight, then compares that figure with the weight on the scale. You choose a carrier divisor and can add the scale weight. The billable weight is the greater of the two. The calculation stays in your browser.

What is dimensional weight (DIM weight)?

Dimensional weight is the shipping weight a carrier works out from a parcel's size, not from the scale. Carriers divide length × width × height by a divisor, then bill the higher of that result and the actual weight. A light, bulky box can cost more to ship than a small heavy one.

How do you calculate dimensional weight in inches and pounds?

Multiply length × width × height in inches, then divide by the carrier's divisor: 139 for FedEx and UPS daily rates, or 166 for USPS Priority Mail once a package is over 1 cubic foot. A 16 × 12 × 10 inch box is 1,920 cubic inches. Divided by 139, that is 13.81 lb, which rounds up to a billed 14 lb.

How do you calculate dimensional weight in centimetres and kilograms?

Multiply length × width × height in centimetres, then divide by 5,000 for FedEx, UPS daily rates, and DHL, or by 6,000 for USPS, UPS retail, and IATA air freight. A 40 × 30 × 25 cm carton is 30,000 cm³. Divided by 5,000, that is exactly 6 kg. If the scale reads 3.5 kg, the carrier bills the 6 kg.

What is billable weight?

Billable weight is the greater of a parcel's scale weight and its dimensional weight, and that is the figure on the courier invoice. This page rounds the higher number up to the next whole pound or kilogram. A 5 kg parcel with an 8.2 kg dimensional weight is billed at 9 kg.

Why do couriers use different DIM divisors like 139, 166, and 5000?

Couriers use different DIM divisors because each tariff sets how much box volume equals one pound or one kilogram. A lower number, such as 139, produces a heavier dimensional weight than 166, so a bulky parcel costs more. In inches, FedEx, UPS daily rates, and DHL use 139, while USPS Priority Mail, UPS retail, and IATA air freight use 166. In centimetres, FedEx, UPS daily rates, and DHL use 5,000. USPS, UPS retail, and IATA air freight use 6,000.

What is FedEx chargeable weight?

FedEx chargeable weight is the greater of the parcel's actual scale weight and its dimensional weight. If the box is light but large, FedEx bills the DIM weight. If the scale weight is higher, FedEx bills the scale weight. The FedEx preset on this page uses 139 for inches and 5,000 for centimetres.

What happens if a parcel exceeds a courier's size or weight limit?

A parcel over the courier's size or weight limit can be charged an oversize or additional-handling surcharge on top of dimensional weight. Many networks flag a length over 108 inches (274 cm), length plus girth over 165 inches (419 cm), or a scale weight over 70 lb (about 32 kg). Those pieces often leave the parcel belt and move as freight. The cutoffs differ by carrier and they change, so check the current rule before you pack.

Dimensional weight calculator

A dimensional weight calculator works out the volumetric weight of a parcel from its length, width, and height, then shows the billable weight a carrier charges. Enter the three dimensions in inches or centimetres, choose a divisor such as 139, 166, or 5000, and add the scale weight if you know it. Billable weight is the greater of the scale weight and the DIM weight. It runs in your browser, and nothing is uploaded.

Calculates client-side · No package dimensions are uploaded

Length (in)

Width (in)

Height (in)

Actual Scale Weight (lbs)

Optional comparison

Carrier Divisor (DIM Divisor)

Select a carrier rule or enter a negotiated custom divisor

Active Divisor:

Dimensional Weight

14 lbs

Exact: 13.81 lbs (billed at rounded integer)

Billable Weight

14 lbs

Determined by DIM weight (exceeds 8 lbs scale weight)

Package Volume

1,920 cu. in.

Equivalent to ~1.111 cu. ft.

Carrier Comparison for 16 × 12 × 10 in

Carrier / Standard	Divisor	Exact DIM Weight	Billed DIM Weight	Billable Result
FedEx (Standard / Express / Ground)Selected	139	13.81 lbs	14 lbs	DIM governs (14 lbs)
UPS (Daily Rates / Commercial)Selected	139	13.81 lbs	14 lbs	DIM governs (14 lbs)
UPS (Retail / The UPS Store)	166	11.57 lbs	12 lbs	DIM governs (12 lbs)
USPS Priority Mail / Express	166	11.57 lbs	12 lbs	DIM governs (12 lbs)
DHL ExpressSelected	139	13.81 lbs	14 lbs	DIM governs (14 lbs)
IATA Air Cargo / Freight	166	11.57 lbs	12 lbs	DIM governs (12 lbs)

Copy dimensions, volume, and dimensional weight breakdown.

Dimensional weight calculator example

Medium box shipped via FedEx Ground

A 16 × 12 × 10 inch package has a volume of 1,920 cubic inches. Using the standard FedEx domestic divisor of 139 yields an exact dimensional weight of 13.81 lbs, billed at 14 lbs. If the scale weight is only 8 lbs, the carrier bills for 14 lbs.

Dimensional weight calculator how-to

Pick the carrier preset (FedEx/UPS 139, UPS retail/USPS 166, DHL, IATA).
Enter length, width, height in the unit system the carrier uses.
Enter actual scale weight if you have it. Billable weight is the greater of actual and dimensional.
If you ship UK domestic Royal Mail, use the parcel size checker instead. Those products are banded, not DIM'd.

Why Dimensional weight calculator matters

Couriers charge on volumetric weight when the box is light for its size. A 30 cm cube of t-shirts can cost more than the same weight in a tight mailer.

The divisor is the whole game: imperial 139 vs 166 changes billable pounds on the same carton. Contract accounts and retail walk-up rates are not the same preset.

Dimensional weight

Imperial: DIM lb = L × W × H (inches) / divisor, often 139 or 166. Metric: DIM kg = L × W × H (cm) / 5000 or 6000. Billable = max(actual, DIM), usually rounded up to the next whole unit. This page uses the divisor you select; it does not apply fuel surcharges.

Dimensional weight calculator limitations

Divisors are the common published ones and can differ on a contract. Royal Mail consumer services do not use this formula.

Related guides

Dimensional weight divisors by carrier
The divisor, not the tape measure, decides whether a light box is billed as a heavy one.
Royal Mail Large Letter vs Small Parcel
The thickness cap on Large Letter is 25 mm. Miss it and Royal Mail consumer postage steps up to Small Parcel.

Related tools

Shipping

Dimensional weight calculator FAQ

What is a dimensional weight calculator?: A dimensional weight calculator turns a parcel's length, width, and height into volumetric weight, then compares that figure with the weight on the scale. You choose a carrier divisor and can add the scale weight. The billable weight is the greater of the two. The calculation stays in your browser.
What is dimensional weight (DIM weight)?: Dimensional weight is the shipping weight a carrier works out from a parcel's size, not from the scale. Carriers divide length × width × height by a divisor, then bill the higher of that result and the actual weight. A light, bulky box can cost more to ship than a small heavy one.
How do you calculate dimensional weight in inches and pounds?: Multiply length × width × height in inches, then divide by the carrier's divisor: 139 for FedEx and UPS daily rates, or 166 for USPS Priority Mail once a package is over 1 cubic foot. A 16 × 12 × 10 inch box is 1,920 cubic inches. Divided by 139, that is 13.81 lb, which rounds up to a billed 14 lb.
How do you calculate dimensional weight in centimetres and kilograms?: Multiply length × width × height in centimetres, then divide by 5,000 for FedEx, UPS daily rates, and DHL, or by 6,000 for USPS, UPS retail, and IATA air freight. A 40 × 30 × 25 cm carton is 30,000 cm³. Divided by 5,000, that is exactly 6 kg. If the scale reads 3.5 kg, the carrier bills the 6 kg.
What is billable weight?: Billable weight is the greater of a parcel's scale weight and its dimensional weight, and that is the figure on the courier invoice. This page rounds the higher number up to the next whole pound or kilogram. A 5 kg parcel with an 8.2 kg dimensional weight is billed at 9 kg.
Why do couriers use different DIM divisors like 139, 166, and 5000?: Couriers use different DIM divisors because each tariff sets how much box volume equals one pound or one kilogram. A lower number, such as 139, produces a heavier dimensional weight than 166, so a bulky parcel costs more. In inches, FedEx, UPS daily rates, and DHL use 139, while USPS Priority Mail, UPS retail, and IATA air freight use 166. In centimetres, FedEx, UPS daily rates, and DHL use 5,000. USPS, UPS retail, and IATA air freight use 6,000.
What is FedEx chargeable weight?: FedEx chargeable weight is the greater of the parcel's actual scale weight and its dimensional weight. If the box is light but large, FedEx bills the DIM weight. If the scale weight is higher, FedEx bills the scale weight. The FedEx preset on this page uses 139 for inches and 5,000 for centimetres.
What happens if a parcel exceeds a courier's size or weight limit?: A parcel over the courier's size or weight limit can be charged an oversize or additional-handling surcharge on top of dimensional weight. Many networks flag a length over 108 inches (274 cm), length plus girth over 165 inches (419 cm), or a scale weight over 70 lb (about 32 kg). Those pieces often leave the parcel belt and move as freight. The cutoffs differ by carrier and they change, so check the current rule before you pack.