Dimensional weight calculator (DIM weight, billable weight & CBM)
Pick a carrier, enter the box size and weight, and see the volumetric weight, the billable weight (the larger of the two, rounded the carrier’s way) and the CBM. Each result shows the formula, the rounding and the official source it comes from.
Calculations run entirely in your browser – the sizes and weights you type are never sent to a server.
Divisors at a glance
| Carrier / rate | Formula | Rounding | Effective |
|---|---|---|---|
| UPS Daily Rates (domestic & international) | L × W × H (in) ÷ 139 = lb | Each side rounded up to a whole inch (min 1 in); dimensional and actual weight rounded up to the next whole lb. | 2026 Daily Rates guide marked “Updated September 7, 2026”; the date the guide took effect could not be verified. |
| UPS Retail Rates – domestic | L × W × H (in) ÷ 166 = lb | Same as Daily Rates: sides rounded up (min 1 in), weight rounded up to whole lb. | Not verified. |
| UPS Retail Rates – export | L × W × H (in) ÷ 139 = lb | Sides rounded up (min 1 in), weight rounded up to whole lb. | Not verified. |
| FedEx Express, Ground, Home Delivery & international (US Service Guide) | L × W × H (in) ÷ 139 = lb | Any fraction of an inch rounded up to the next whole inch; any fraction of a pound rounded up to the next pound. Billed on “the greater of the package’s actual rounded weight or dimensional weight”. | Service Guide 2026 effective Jan 5, 2026 (updated Sep 11, 2026); rounding each side up to the next inch effective Aug 18, 2025. |
| FedEx International Deferred Freight | L × W × H (in) ÷ 166 = lb | Same as other FedEx services. | Service Guide 2026 (effective Jan 5, 2026). |
| USPS Priority Mail Express, Priority Mail, Ground Advantage, Parcel Select (retail & commercial) – from Jul 12, 2026 | If L × W × H (in) [× 0.785 if non-rectangular] > 1,728: ÷ 139 = lb | Each side rounded up to the nearest whole inch (DMM 604.7.0); dimensional weight rounded up to the next whole lb. Above 70 lb the 70 lb price applies. | From July 12, 2026 (DMM changes marked [7-12-26]; Postal Bulletin 22705). |
| USPS Commercial Priority Mail – non-rectangular (DMM 223 text as published) | L × W × H (in) × 0.785; if > 1,728: ÷ 166 = lb | Each side rounded off (nearest whole inch); dimensional weight rounded up to the next whole lb. | Current DMM 223 text; this paragraph has no [7-12-26] mark. Whether USPS actually bills this way could not be verified. |
| USPS – rule before Jul 12, 2026 | If L × W × H (in) [× 0.785] > 1,728: ÷ 166 = lb | Each side rounded off to the nearest whole inch; dimensional weight rounded up to the next whole lb. | Until July 11, 2026. |
| DHL Express (cm / kg) | L × W × H (cm) ÷ 5,000 = kg | Dimensions: no official rounding found (not rounded). Weight: rounded up to the next 0.5 kg (DHL Express UK FAQ: “rounded up to the nearest half kilo”); other countries not verified. | No effective date found. |
| DHL Express (in / lb) | L × W × H (in) ÷ 139 = lb | Dimensions not rounded. Weight rounding in lb (whole lb or 0.5 lb) could not be verified – default whole lb, you can change it. | No effective date found. |
| DHL eCommerce US (in / lb) | L × W × H (in) ÷ 166 = lb | Not stated by DHL. Default: round to the nearest whole lb, because DHL’s own example writes 2,160 ÷ 166 = 13.01 as “13 lbs” (not rounding would show 13.01; rounding up would give 14). Round up is available as an option. Unverified – your DHL invoice is final. | No effective date found. |
| DHL eCommerce US (cm / kg) | L × W × H (cm) ÷ 6,000 = kg | Not stated by DHL – not rounded by default; choose a rounding if your bill shows one. | No effective date found. |
Sources and the full text of each rule: rule sources (checked 2026-10-29).
Worked example
- A 15.1 × 10 × 6 in box weighing 3 lb, UPS Daily Rates: sides round up to 16 × 10 × 6 = 960 in³.
- 960 ÷ 139 = 6.91 → rounded up to 7 lb.
- Billable weight = the larger of 3 lb and 7 lb = 7 lb. At UPS Retail (÷166) the same box is 6 lb.
FAQ
What is dimensional weight?
Carriers price a parcel by the larger of its actual weight and a weight worked out from its size: length × width × height divided by a divisor (DIM factor). That larger number is the billable weight.
Which divisor should I use?
Published US rates: UPS Daily Rates 139, UPS Retail domestic 166, FedEx 139, USPS 139 (from July 12, 2026, only above 1 cubic foot), DHL Express 5,000 (cm/kg) or 139 (in/lb), DHL eCommerce US 166 (in) or 6,000 (cm). Contract rates can use a different divisor – use the Custom divisor option.
Why does my invoice differ from this calculator?
Carrier pages sometimes disagree about rounding, your contract may set its own divisor, and surcharges are not included. Your carrier’s invoice is final; you can switch the rounding where the sources conflict.
What is CBM?
CBM is cubic metres: length × width × height in metres (1 CBM = 1,000,000 cm³). Freight forwarders use it for sea and air quotes.
Are the sizes and weights I enter sent anywhere?
No. All calculations run in your browser and the site has no backend. The site uses cookieless Cloudflare Web Analytics only to count anonymous visits; see the privacy page.