Semi truck dimensions: length, width and height

The diagram labels the dimensions people ask about most. Width is a federal limit. Height is set by states, and the 13 feet 6 inches shown is a common figure, not a national rule. Overall length is a typical range, because it depends on the tractor.

How wide is a semi truck?

Under 23 CFR 658.15, vehicles on the National Network may be up to 102 inches wide. Rear-view mirrors, turn signals, handholds and certain other safety devices are not counted, within limits set in the rule. Most modern tractors and trailers are built to the full 102 inches.

Source: 23 CFR 658.15, checked October 2026

Loads wider than the legal limit, such as wide machinery on a flatbed or step deck, need an oversize permit from each state on the route, and often escorts and travel time restrictions.

How long is a semi truck?

Trailer length

Federal rules, in 23 CFR 658.13, require states to allow semitrailers of at least 48 feet in a tractor-semitrailer combination on the National Network, and they do not set an overall length limit for that combination. Most states allow 53 foot trailers, which have become the standard for dry vans and reefers. Some states also limit the kingpin to rear axle distance; California, for example, limits it to 40 feet for most trailers with two or more axles.

Source: 23 CFR 658.13, checked October 2026

Tractor length

Tractor length varies far more than trailer length. A day cab is the shortest. A sleeper adds length, and large sleepers add more. As a result, a tractor with a 53 foot trailer often comes to roughly 70 to 80 feet overall, measured bumper to bumper.

Box trucks

Box trucks are described by the length of the cargo box, such as 26 feet. Overall vehicle length is longer, because it includes the cab and any overhang. The box length is what decides how much freight fits.

How tall is a semi truck?

There is no federal height limit. Each state sets its own, and many eastern and central states use 13 feet 6 inches, while several western states allow 14 feet. Many trailers are built about 13 feet 6 inches tall so they are legal almost everywhere.

The number that matters on the road is the clearance under bridges, overpasses, drive-throughs and parking structures, which can be lower than the state limit. Posted clearances are not always accurate, and snow, fresh pavement and load changes can all reduce the margin. Know your rig's actual height. Our guide to semi truck height clearance explains how to measure it and plan routes.

Trailer inside dimensions

Inside dimensions are what decide how many pallets fit.

• Inside width of a 102 inch dry van is typically a little over 8 feet, because of the walls.
• Inside height of a dry van is commonly around 9 feet, less at the rear door frame.
• Reefer trailers have thicker insulated walls, so inside width and height are a little smaller.
• Pallet count. A 53 foot trailer commonly fits 26 standard pallets in two rows on the floor, depending on pallet size and loading pattern.

Check the trailer maker's spec sheet for exact inside dimensions; they differ between models.

Flatbed, step deck and reefer dimensions

Open-deck trailers change the height question, because the load sits on top of the deck. A flatbed's deck is commonly around 5 feet off the ground, so freight taller than about 8 and a half feet can push the total past 13 feet 6 inches. A step deck has a lower rear deck, which lets taller freight stay within height limits. A reefer trailer is built to the same outside limits as a dry van but has slightly smaller inside dimensions because of its insulated walls.

Exact deck heights depend on the trailer model and its tires and suspension. Measure your own trailer and keep the number with your paperwork, so you can check a load's height before it is loaded.

Doubles and other combinations

The same federal rule that protects 48 foot semitrailers also requires states to allow trailers of at least 28 feet in a twin-trailer combination on the National Network. Longer combination vehicles, such as triples and long doubles, are allowed only in some states and on certain routes. Our dispatch desk works with single-trailer combinations and straight trucks.

Measuring your own rig

Published dimensions are a starting point, but your truck may differ because of tires, suspension, the fifth wheel height and any equipment on the roof. Measure:

1. Overall height at the highest point, often the trailer roof or a roof fairing, on level ground with normal tire pressure.
2. Overall length from the front bumper to the rear of the trailer.
3. Width at the widest point other than mirrors.

Write the numbers on a label inside the cab. A driver who knows the rig is 13 feet 6 inches tall can make a quick decision at a low bridge sign instead of guessing.

Box truck dimensions

A 26 ft box truck has a cargo box about 26 feet long, with inside width and height that vary by body maker but are often close to 8 feet each. Overall height, including the cab and box, is usually lower than a semi trailer, but it still matters at drive-throughs, parking garages and low bridges. Check the body maker's plate for exact inside dimensions before quoting pallet counts.

Dimensions and fuel economy

Size affects fuel use, mostly through aerodynamic drag. A tall, square trailer pushes a lot of air, and the gap between the tractor and trailer adds turbulence. That is why many highway tractors use high roofs and side fairings that match the trailer's height and close the gap, and why trailer skirts and tails have become common on dry vans and reefers. For flatbeds and car haulers, the load itself shapes the drag, so the same truck can see very different fuel economy from one load to the next.

Tires and dimensions

Tire size changes ride height and the overall height of the rig a little, and it matters for gearing and speedometer accuracy. Our guide to semi truck tire size explains how to read the size on the sidewall.

Inside the cab

Cab dimensions decide how comfortable a truck is to live in: sleeper length, roof height and bunk size. Our guide to the semi truck interior covers sleeper types and layouts. If you are checking a used truck's specs, the semi truck VIN decoder confirms the make, model and year.

Dimensions and dispatch

When we look at a load, we check that it fits the trailer by length, width, height and weight, and that the route suits the rig, including low clearances and restricted roads. Oversize loads need permits and route planning; we do not issue permits, but we account for them when quoting.

Where we fit

We dispatch 26 ft box trucks and larger across 11 equipment types and plan loads that fit your equipment. Learn more about our dispatch service.