Quick answer
Dimensional weight = length × width × height ÷ divisor. A 20 × 15 × 10 inch box with a divisor of 139 gives 3,000 ÷ 139 = 21.58 lb; carriers bill the larger of the dimensional and the actual weight.
Enter the box dimensions, the carrier's divisor and, optionally, the actual weight. The calculator shows the dimensional weight and the billable weight.
Related tools: Weight Converter: Convert kilograms, pounds, ounces, stone and more. Power-to-Weight Ratio Calculator: Power per unit weight of a vehicle. Ideal Weight Calculator: Ideal body weight by four published formulas (Devine, Robinson, Miller, Hamwi).
How to use the Dimensional Weight Calculator
- Enter length (in) (above 0).
- Enter width (in) (above 0).
- Enter height (in) (above 0).
- Enter carrier divisor (in³/lb) (above 0).
- Optionally, enter actual weight (optional) (lb) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Length | A number, in in | > 0 |
| Width | A number, in in | > 0 |
| Height | A number, in in | > 0 |
| Carrier divisor | A number, in in³/lb. Set by each carrier; check their rate guide | > 0 |
| Actual weight (optional) (optional) | A number, in lb | > 0 |
Formula and method
Formula
dimensional weight = L × W × H ÷ divisor
IEEE-754 double precision; shown to the decimals indicated.
Carriers use different divisors and rounding, so enter the one from your rate guide.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Length = 20; Width = 15; Height = 10; Carrier divisor = 139; Actual weight (optional) = 12.
| Result | Value |
|---|---|
| Dimensional weight | 21.58 lb |
| Billable weight | 21.58 lb |
Example 2
Inputs: Length = 12; Width = 12; Height = 12; Carrier divisor = 139.
| Result | Value |
|---|---|
| Dimensional weight | 12.43 lb |
| Billable weight | 12.43 lb |
Example 3
Inputs: Length = 40; Width = 30; Height = 20; Carrier divisor = 166; Actual weight (optional) = 60.
| Result | Value |
|---|---|
| Dimensional weight | 144.58 lb |
| Billable weight | 144.58 lb |
The first line is the headline result (dimensional weight). Below it the dimensional Weight Calculator lists billable weight, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
The divisor sets the answer
A divisor of 139 is the one commonly published for UPS and FedEx domestic shipments in inches and pounds, while other carriers and international services use different values (for example 166). A smaller divisor makes light, bulky boxes cost more. Always use the divisor from your carrier's current rate guide.
Reducing billable weight
Because the box volume is in the numerator, trimming one inch off a dimension reduces the figure noticeably. For this box, 20 × 15 × 9 gives 2,700 ÷ 139 = 19.42 lb.
How the result changes with length
Holding every other input at the first worked example, this table changes only length. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Length | Dimensional weight | Billable weight |
|---|---|---|
| 10 | 10.79 lb | 12 lb |
| 20 | 21.58 lb | 21.58 lb |
| 40 | 43.17 lb | 43.17 lb |
| 80 | 86.33 lb | 86.33 lb |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Length: entering "0" shows "Length must be greater than 0." beside that field and no result.
- Carrier divisor: entering "0" shows "Carrier divisor must be greater than 0." beside that field and no result.
Choosing between the Dimensional Weight Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Weight Converter](/converters/weight-converter/) | value, from and to | Pound (lb) → Gram (g) |
| [Power-to-Weight Ratio Calculator](/engineering/power-to-weight-ratio/) | power, power unit and weight | Power-to-weight |
| [Ideal Weight Calculator](/health/ideal-weight-calculator/) | units, sex and height | Ideal weight (Devine) |
| [Weight Gain Calculator](/health/weight-gain/) | units and gain per week | Daily calorie surplus |
| [Pipe Weight Calculator](/construction/pipe-weight/) | outside diameter, wall thickness and length | Pipe weight |
Assumptions and limitations
- Billable weight is the larger of actual and dimensional
Use results as engineering estimates and check them against the governing standards, safety factors and a qualified engineer's judgement before relying on them.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for length and carrier divisor to confirm this.
Frequently asked questions
What is billable weight?
The greater of actual weight and dimensional weight.
Do I round dimensions?
Carriers usually round each dimension up to the next whole inch and the result up to the next pound; check their rules.
Does it work in centimetres?
Use the divisor for centimetres and kilograms from the carrier (for example 5,000 or 6,000 cm³/kg).
What does the Dimensional Weight Calculator calculate?
Dimensional (volumetric) weight using a carrier divisor you enter. It returns Dimensional weight and Billable weight.
What formula does the Dimensional Weight Calculator use?
dimensional weight = L × W × H ÷ divisor. Carriers use different divisors and rounding, so enter the one from your rate guide.
What do I need to enter in the dimensional Weight Calculator?
You enter Length (in), Width (in), Height (in) and Carrier divisor (in³/lb). Optional: Actual weight (optional) (lb).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Billable weight is the larger of actual and dimensional.
What is an example of a dimensional Weight result?
With length 20, width 15, height 10, carrier divisor 139 and actual weight (optional) 12, the dimensional weight is 21.58 lb.
Where does the method come from?
The method follows: Carrier rate guides (divisors differ by carrier and service).
Can I rely on this calculator for a decision?
Use results as engineering estimates and check them against the governing standards, safety factors and a qualified engineer's judgement before relying on them. For this calculator in particular: Billable weight is the larger of actual and dimensional.
Related calculators
- Weight Converter — Convert kilograms, pounds, ounces, stone and more.
- Power-to-Weight Ratio Calculator — Power per unit weight of a vehicle.
- Ideal Weight Calculator — Ideal body weight by four published formulas (Devine, Robinson, Miller, Hamwi).
- Weight Gain Calculator — Daily calorie surplus for a target weekly weight gain.
- Pipe Weight Calculator — Weight of a hollow round pipe from its outside diameter, wall thickness and length.
- Water Weight Calculator — Weight of a volume of water at a given temperature.
Sources
- Carrier rate guides (divisors differ by carrier and service)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.