Shipping tools that answer the question.
Free calculators for package size, dimensional weight, box fit, carrier limits, and seller profit. No sign-up, no guessing, and a straight answer when we do not have the data to be sure.
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How we handle carrier rules
Carrier limits and dimensional weight divisors change, and a stale number presented confidently is worse than no number. So every carrier-dependent answer on this site tells you which ruleset it used, when that rule was last checked, and links to the official source.
Right now 0 of 16 rules in our 2026-08-30 snapshot have been re-verified against their official sources, and every result says so. Where we have no verified rule at all — the FedEx dimensional weight divisor, for instance — the tools tell you they cannot answer rather than filling in a plausible figure.