Dimensional Weight (DIM) Shipping Calculator

Last updated 2026-08-17

Most carriers bill you for whichever is larger: your package's actual weight, or its dimensional weight — a stand-in for size, calculated as length × width × height ÷ divisor. A big, light box can cost more to ship than a small, heavy one. The divisor is what turns box volume into pretend pounds or kilograms, and it is set by each carrier, for each service, and it changes.

Why there is no built-in carrier table Calculators that hardcode "UPS = 139, FedEx = 139, DHL = 5000" go stale the moment a carrier revises its rates, and nothing on the page would tell you. This one asks for your divisor instead. We verified exactly one figure from a carrier's own current documentation this session — USPS, below. UPS's and DHL's own sites did not load (timeouts, tried more than once, on several distinct URLs) and FedEx's returned a bot-block error page on every URL tried, so we are not printing numbers for them rather than guessing. Get your own carrier's current published divisor and enter it — that number is the one your invoice will actually use.

How this is calculated

Dimensional weight = (L × W × H) ÷ divisor, rounded up to the next whole unit — that rounding-up rule is stated explicitly on USPS's own page, the one figure we verified, and we apply it uniformly here since it is standard practice across carriers we could not fetch. Billable weight is whichever is larger, actual or dimensional. When dimensional weight wins, the gap between it and your actual weight is what you are paying to ship as empty space, not product.

What this does not do

It does not tell you your carrier's current divisor. Get it from your carrier's own rate page or account — the one example above is the only one we could verify this session.
It does not add fuel surcharges, zone pricing, or minimum-billable-weight rules — those vary by carrier and service and are not part of the dimensional-weight calculation itself.
It does not store or send anything. All three numbers stay in your browser.

Runs entirely in your browser. Nothing you type is sent anywhere. Storage pricing has the same trap in a different shape — the sticker price isn't the effective cost — which is what the cloud storage effective cost calculator is for.