Shipping calculators
Work out what a carrier will actually bill you for, before you hand the parcel over. These cover the rules that decide your invoice — divisors, rounding, girth limits, surcharges and cut-offs — with the current figures for every major carrier.
10 calculators · last reviewed
The rule that catches most people out
Carriers do not bill the weight on your scales. They bill the greater of that and a figure derived from the box's size, because a van runs out of space long before it runs out of payload. A box of cushions and a box of books take the same room on the vehicle, so the cushions get billed as though they were heavier.
The arithmetic is simple — length times width times height, divided by a number — but that number differs by carrier, by unit system and sometimes by how you bought the label. UPS uses 139 on an account and 166 over the retail counter, which means the same parcel is cheaper on dim weight if you walk into a store. And in July 2026 USPS moved from 166 to 139, adding roughly 19% to the billable weight of every parcel over a cubic foot.
That last change is recent enough that several of the calculators still ranking for these searches print the old figure. If a tool tells you a 14 by 12 by 12 inch box bills at 13 pounds with USPS, it is running on pre-July rules — it is now 15. And if it returns any dimensional weight at all for a 12 inch cube, it has missed the threshold entirely: at exactly 1,728 cubic inches that parcel does not qualify.
Why we do not quote you a price
Every site that hands you a precise shipping price is showing you one of two things: their own negotiated rate, which you cannot buy, or a number with no source behind it. During our audit of this market we found a page ranking on the first page for a rate-calculator query that returned "No shipping rates found", and another whose calculator URL simply 404s.
So our cost tools take your rate as an input — the one your carrier quoted, or your contract rate — and get exactly right the part that goes wrong in practice: the chargeable weight that rate is multiplied by, the fuel and accessorial surcharges stacked on top, and the duty waiting at the border.
Reducing what you pay
In rough order of how much money each one moves:
- Right-size the carton. Taking two centimetres off each side of a 40 × 30 × 20 cm box removes about 14% of the volume. If that drops you under a rounding threshold, the saving is bigger than the arithmetic suggests.
- Check the girth, not just the length. Oversize and additional-handling surcharges are triggered by combined length and girth, and they are frequently larger than the base shipping charge.
- Watch the divisor, not the brand. The cheapest carrier for a bulky parcel is often not the cheapest for a dense one, because the divisor decides how hard your empty space is taxed.
- Ask what the fuel surcharge is today. It resets weekly. A quote given three weeks ago was calculated against a different number.
Common questions
Which shipping calculator should I start with?
If you want to know what a carrier will bill, start with the chargeable weight calculator — it compares your scale weight against the volumetric figure and applies the carrier's rounding. If you are comparing carriers, use the courier comparison, which runs one parcel through every carrier's rules at once.
Do these work outside the United States?
Yes. Everything takes metric or imperial input, and the carrier list covers DHL, FedEx, UPS, USPS, Royal Mail, Evri, DPD, Delhivery, Blue Dart, DTDC, Xpressbees, Ekart, India Post, Aramex, Canada Post, Australia Post, LBC and J&T. Currency is selectable across twenty options.
Why does my invoice come in higher than the quote?
Almost always one of four things: the carrier remeasured the parcel and billed dimensional weight, a residential or remote-area surcharge applied, the fuel surcharge moved between quote and billing, or the address needed correcting. The shipping cost calculator lets you model all four so you can see which one it was.