Guides · LoadLegit

Guides: truck weight limits & axle compliance

Practical, math-honest guides on axle weights, the Federal Bridge Formula, tandem slides and load planning — from the team behind the free axle weight calculator.

The Federal Bridge Formula, explained (with the exact math)

What the Federal Bridge Formula is, the exact W = 500(LN/(N-1) + 12N + 36) math, why a truck under 80,000 lb can still be illegal, and how to check it in seconds.

Looking for your state? See truck weight limits by state.