Estimate a package’s dimensional weight — the weight shipping carriers bill for large-but-light packages instead of actual weight.
How it works
Dimensional weight is (length × width × height) ÷ divisor. A 20×15×10 inch box using the common 139 divisor works out to about 21.6 lb of dimensional weight.
What this does not include
139 is a typical US domestic divisor, not universal — carriers and service levels use different values (some international air services use 166), so check your specific carrier’s rate sheet and adjust the divisor here to match.
How to use this calculator
- Enter the package’s length, width, and height.
- Adjust the divisor to match your carrier if needed.
A worked example
A package 20 × 15 × 10 inches, divisor 139 (a common air freight standard): dimensional weight = (20×15×10) ÷ 139 = 21.5827 lb.
A 12 × 12 × 12 inch box, same divisor: dimensional weight = 12.4317 lb.
What the variables mean
| Variable | Meaning |
|---|---|
| Length, width, height | Package dimensions |
| Divisor | A carrier-specific constant reflecting how much space “costs” relative to weight |
Edge cases worth knowing
Carriers bill based on whichever is greater — actual weight or dimensional weight. A large, lightweight package (like packing peanuts around a small item) can cost more to ship than its actual weight alone would suggest.
Different carriers use different divisors — 139 is common for international air freight, but domestic carriers often use other values, so the right divisor depends on which shipping service is being used.
Why do carriers bill dimensional weight instead of actual weight?
A large, lightweight box still takes up truck and plane space that could carry a heavier shipment, so carriers charge based on whichever is greater — actual weight or dimensional weight — to account for that space.
How do I know which weight I’ll actually be charged?
Compare this calculator’s dimensional weight result against the package’s actual scale weight — carriers bill whichever number is higher.
Does packaging material count toward the dimensions?
Yes — measure the outer dimensions of the box as shipped, including any padding or packaging, not just the product inside.
