Guides · LoadLegit · 2026-08-04

US vs Canada truck weight limits: what changes at the border

If you run cross-border lanes, the single most expensive mistake is assuming one set of weight limits covers both countries. It doesn't. A load that is perfectly legal on the Canadian interprovincial network can put you over a US federal limit the moment you cross, and the reverse happens too. Here's exactly what changes.

The headline numbers, side by side

Two things jump out. First, Canada's gross and tandem limits are higher — roughly 7,000 lb more gross and 3,500 lb more per tandem. Second, the US adds a bridge-formula check that Canada doesn't have, which can make the US stricter on tightly-spaced axle groups even though its headline gross limit is lower.

The trap: legal in Canada, illegal in the US

Because Canada allows more gross weight, a load built to Canadian limits routinely fails a US check. Take a rig grossing 84,000 lb (about 38,100 kg). In Canada that's under the 39,500 kg MOU gross limit — legal. Cross into the US and it's 4,000 lb over the 80,000 lb federal gross limit, before the bridge formula even runs. That's an out-of-service order and a fine, on a load that was compliant an hour earlier.

The reverse trap: the bridge formula

Going the other way, a US-legal load is almost always fine on gross weight in Canada (Canada allows more). But don't assume the axle spacings that satisfied the US bridge formula map cleanly onto Canadian tandem/tridem spread windows — the group definitions differ. Re-check the configuration against MOU spreads rather than trusting the US result.

How to plan a cross-border load

1. Decide which limit governs each leg. Check the load against US federal rules for the US portion and MOU rules for the Canadian portion — separately.
2. Work in the right units. Canada is metric; a mental "×2.2" is fine for a sanity check, but plan on the actual limits, not conversions of the other country's numbers.
3. Watch the gross ceiling. If you loaded to Canadian gross, you likely need to be under it to enter the US legally.
4. Confirm state and provincial specifics. Federal/MOU limits are the baseline; individual US states and Canadian provinces diverge.

Check both sides before you load

Our free calculator runs US federal (with the bridge formula, in pounds) and Canada MOU (in kilograms, no bridge formula) — switch regions to compare the same load against both. For the Canadian rules in depth, see the interprovincial MOU explained.

Compliance guidance, not legal advice — always confirm with the governing authority on each side of the border.