Dimensional Weight Calculator
Big, light boxes cost more than the scale says. Carriers charge the greater of actual and dimensional weight; this shows both before the invoice surprises you.
Your results
Worked example
A 40 x 30 x 20 cm box weighing 3 kg
Volume: 40 × 30 × 20 = 24,000 cm³. Dimensional weight at the 5000 divisor: 24,000 ÷ 5,000 = 4.80 kg. Billable weight is the greater of 4.80 and 3.00, so 4.80 kg, costing 4.80 × $12.00 = $57.60 at the example rate.
In imperial, a 16 x 12 x 8 in box: 1,536 in³ ÷ 139 = 11.05 lb dimensional weight.
How this calculator works
dimensional weight = (length × width × height) ÷ divisor, where the divisor packs the carrier's density assumption into one number: 5000 cm3/kg internationally, 139 in3/lb in North America (the two are nearly equivalent). billable weight = max(actual, dimensional). Carriers round billable weight up to their billing increment (often 0.5 kg or 1 lb), so treat this as the floor, not the invoice.
Some services and rate tiers use different divisors (4000 to 6000, or 166 for some US domestic products). The divisor is an input here; your carrier's tariff or rate guide is the authority for your account.
Common questions
Why does my light box cost so much?
Truck and aircraft space is the scarce resource. A box of pillows fills the same cube as a box of books, so carriers price the cube. Compress packaging, vacuum-bag soft goods, and avoid oversize boxes to cut dimensional weight.
Which divisor does Canada Post or UPS use?
It depends on the service and whether the shipment is domestic or international. Canada Post publishes a volumetric divisor per service; UPS and FedEx commonly use 139 in3/lb (5000 cm3/kg) internationally and different values domestically. Enter the divisor from your rate guide.
Do carriers round up?
Yes, most round billable weight up to the next 0.5 kg or 1 lb, and dimensions up to the next unit. Measure the sealed box, including bulges, not the product inside.
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Estimates only, using the dimensions, divisor and rate you enter. Your carrier's tariff governs billing, including rounding rules.