Understand the estimate
How package size becomes shipping weight
A parcel can be light on a scale but still occupy valuable vehicle and aircraft space. Volumetric weight gives that space a comparable weight, while the estimated billable weight uses whichever is higher: the scale weight or the volumetric result.
Worked example
Why a light, large box may cost more
Suppose a sealed box measures 60 × 40 × 40 cm, weighs 5 kg, and its service uses a divisor of 5000.
60 × 40 × 40÷5000=19.2 kg
The volumetric result is 19.2 kg, which is higher than the 5 kg scale weight. The page therefore shows 19.2 kg as the estimated billable weight. A carrier may then apply its own measurement increments, minimums, and rounding.
If the scale reports ounces, use the Ounces to Grams Calculator to normalize the actual mass before comparing it with volumetric weight. A mass conversion does not convert box capacity or choose a carrier divisor.
For palletized LTL freight, where cubic feet and shipment weight feed a density review, use the Freight Class Calculator. Parcel volumetric divisors and NMFC freight-density classes are different rating methods, so do not substitute one for the other.
Volume conversion
How to calculate box capacity in liters and m³
Keep all three dimensions in centimeters before multiplying them.
1Find cubic centimeters40 × 30 × 30 = 36,000 cm³
2Convert to liters36,000 ÷ 1,000 = 36 L
3Convert to cubic meters36,000 ÷ 1,000,000 = 0.036 m³
Service-specific input
How to choose a volumetric divisor
The divisor can change by carrier, country, route, transport mode, service level, and negotiated contract. Treat this table as a comparison guide, then check the current terms for the exact shipment.
If you already have a dated FedEx quote, the FedEx Shipping Calculator can reconcile its entered package basis, divisor, surcharges, and all-in total; it does not supply a divisor for an unrelated carrier or contract.
A published metric example from DHL Express uses length × width × height ÷ 5000. That example is useful for checking the arithmetic; it does not make 5000 the correct divisor for every shipment.
Practical packing
Ways to reduce volumetric weight
Repack safely first; a smaller number is not useful if the contents are damaged. Once the sealed dimensions and weight are known, the USPS Shipping Calculator can compare its bounded current USPS services where applicable; reducing volume alone does not select an eligible service or postage price.
- Choose the closest safe box
Extra centimeters are multiplied across three dimensions, so unused space adds up quickly.
- Arrange products before sizing
Rotate, nest, or separate items when doing so reduces voids without creating damage risk.
- Use protective fill deliberately
Use enough cushioning for the contents and carrier handling, but avoid an oversized box filled mostly with air.
- Measure after sealing
Bulges, handles, and protrusions can change the outermost dimensions used for rating.
Frequently asked questions
Volumetric weight FAQ
What is the difference between actual, volumetric, and billable weight?
Actual weight is what the sealed parcel weighs on a scale. Volumetric weight converts the space it occupies into a weight using the entered divisor. This page estimates billable weight as the higher of those two values, before any carrier-specific minimum, increment, or rounding rule is applied.
Should I measure the inside or outside of the box?
For a shipping estimate, measure the finished parcel at its outermost length, width, and height after it is packed and sealed. Interior dimensions are useful for box capacity, but they can understate the space the shipment occupies.
How do I calculate cubic meters and liters from centimeters?
Multiply length × width × height to get cubic centimeters. Divide that number by 1,000 for liters or by 1,000,000 for cubic meters. For example, 40 × 30 × 30 cm is 36,000 cm³, 36 L, or 0.036 m³.
Which volumetric divisor should I choose?
Use the divisor published for the exact carrier, service, route, package type, and contract you are quoting. If you do not yet have those terms, 5000 can be used as a comparison reference, but the result must remain an estimate.
How should I calculate several parcels?
Measure and calculate each finished parcel separately because sizes and chargeable-weight rounding can differ. Do not add all dimensions together. Apply the carrier’s rules to each piece, then total the resulting charges or billable weights as instructed.