Truck weight limit checker
Enter your axle weights, axle count and the distance from first to last axle. The checker tests each federal limit and shows which one you're closest to.
By Gustavo · Updated October 2026
FEDERAL INTERSTATE CHECK
- Drive tandem (limit 34,000)
- 33,500 lb
- Trailer tandem (limit 34,000)
- 33,000 lb
- Gross (limit 80,000)
- 78,500 lb
- Bridge formula (limit 80,000)
- 78,500 lb
Legal on these numbers. We check weights on every rate con so it stays that way.
How the checker works
The tool runs four checks against the federal Interstate limits:
- Drive tandem at or under 34,000 lb.
- Trailer tandem at or under 34,000 lb.
- Gross at or under 80,000 lb.
- Bridge formula for the whole rig: W = 500 x (LN / (N - 1) + 12N + 36), rounded to the nearest 500 lb, capped at 80,000.
If any check fails, the rig needs a lighter load or an overweight permit.
SOURCE: Limits: 23 CFR 658.17 and the FHWA bridge formula guide (checked Oct 2026).
Worked example
EXAMPLE
- Steer
- 12,000 lb
- Drive tandem (34,000)
- 33,500 lb
- Trailer tandem (34,000)
- 33,000 lb
- Bridge, 5 axles, 51 ft
- 80,000 lb
This five-axle rig is legal. Now shorten the spread to 40 ft with the same axles: the bridge formula drops to 73,000 lb, and the same freight is 5,500 lb over. Sliding the trailer tandems forward to fix a heavy drive axle can create exactly that problem.
One exception: two tandems at least 36 ft apart may carry 34,000 lb each, even where the formula gives less.
DOT weight limits the checker skips
- State roads. States set limits off the Interstate, and some allow more through grandfather rules or permits.
- Tire and axle ratings. A tire rated for less than the axle limit lowers your legal weight.
- Steer axle. No separate federal number beyond the single axle, but tire ratings usually cap it near 12,000 lb on a tractor.
- Seasonal limits. Frost laws in northern states cut weights on some roads in spring.
Lighter rigs
Hotshots and 26 ft box trucks rarely hit the 80,000 lb limit. Their limits are the truck and trailer ratings: GVWR and GCWR. For those, use the hotshot GCWR and non-CDL weight checker or the max payload calculator.
Good and bad results
Get a certified scale ticket when you're unsure. Most truck stop scales print one in a few minutes, and a reweigh after a fix is cheap compared with an overweight fine.
A pass with less than 500 lb to spare on any axle is a warning. Posted weights are estimates, and a scale ticket can surprise you. A fail means one of three things: move weight between axles (slide the fifth wheel or tandems), take less freight, or get a permit before the load moves.
Weights checked before you say yes
We check the posted weight and ask the broker for the real one before we bring you a load. If it won't scale legal on your rig, it doesn't reach you. You approve every load, and the rate confirmation comes straight to you. See how it works for hotshot dispatch.
Questions about this calculator
Q01What are the DOT weight limits per axle?
On the Interstate system, federal limits are 20,000 lb on a single axle, 34,000 lb on a tandem axle and 80,000 lb gross, with the bridge formula limiting weight on any group of axles. States set limits on other roads and can grandfather higher ones.
Q02What is the semi truck weight limit?
80,000 lb gross on the Interstate system for a typical five-axle tractor-trailer, as long as each axle and axle group is legal. Over that needs an overweight permit.
Q03What is the box truck weight limit?
A box truck can't legally run above its GVWR, the rating on the door jamb. For a 26 ft box truck that's often 26,000 lb or just under. Axle limits and the tire ratings also apply.
Q04Does the steer axle have a federal limit?
The single-axle limit of 20,000 lb applies, but steer axles are normally limited lower by tire and axle ratings. About 12,000 lb is a common working figure for a tractor. Some states limit weight per inch of tire width.
Q05What is the bridge formula?
W = 500 x (LN / (N - 1) + 12N + 36), where L is the distance in feet between the outer axles of a group and N is the number of axles. It spreads weight so bridges aren't overstressed.