Big Rigs · Nationwide · October 25, 2026

How Much Does a Semi Truck Weigh?

By Big Rig Daily Staff

A semi truck can weigh up to 80,000 pounds (40 tons) on the Interstate System, the federal maximum gross weight, unless the Bridge Formula sets a lower limit. Empty, it weighs far less. A typical Class 8 sleeper tractor weighs about 20,000 pounds (10 tons), according to the National Academies, and the popular 53-foot dry van trailer weighs roughly 14,000 pounds (7 tons). Weights here are in pounds and U.S. short tons of 2,000 pounds.

The 80,000 pound figure is a legal limit, not a typical weight, and many loads weigh less. To check axle loads against the limits, use the truck weight and axle calculator.

Semi truck weight at a glance

• Fully loaded, legal maximum: up to 80,000 lb (40 tons) on the Interstate System, per 23 CFR 658.17
• Tractor only: about 20,000 lb (10 tons) for a typical Class 8 sleeper tractor, per the National Academies
• Empty 53-foot dry van: roughly 14,000 lb (7 tons), per the National Academies
• Empty all-aluminum flatbed: roughly 8,300 to 9,000 lb (about 4 to 4.5 tons), per Fontaine and Wabash spec sheets
• Maximum payload for a typical sleeper and 53-foot dry van: about 46,000 lb (23 tons), per the National Academies

Typical weights vary by make, sleeper size, engine, fuel load and trailer type. Legal limits come from federal law and do not change with the truck.

How much does a semi tractor weigh?

The National Academies, in a report on reducing truck fuel use, says: "The typical Class 8 sleeper tractor weighs about 20,000 pounds." Weight varies by make, sleeper size, engine and fuel load.

Day cabs weigh less than sleepers because they have no sleeper berth.

What is a Class 8 truck?

Class 8 covers trucks with a gross vehicle weight rating (GVWR) of 33,001 pounds or more, according to the U.S. Department of Energy's vehicle weight class table. Class 7 runs from 26,001 to 33,000 pounds. Class 8 is a rating category, not what the truck actually weighs on a scale.

How much does an empty semi trailer weigh?

Dry van

The National Academies says "the popular 53-foot dry van trailer weighs roughly 14,000 pounds." That is about 7 tons.

Reefer

Reefers weigh more than dry vans because of the refrigeration unit and insulation.

Flatbed

All-aluminum flatbeds from Fontaine and Wabash are listed at roughly 8,300 to 9,000 pounds for base models. Wabash's figures are for a 48-foot trailer, and Fontaine lists its weights as approximate, within 3 percent. Steel and combo flatbeds weigh more.

Semi truck weight limits: gross and axle

Federal gross and axle limits

23 CFR 658.17 sets these limits on the Interstate System:

• Gross weight: 80,000 pounds, "except where lower gross vehicle weight is dictated by the bridge formula"
• Single axle: 20,000 pounds
• Tandem axle: 34,000 pounds. The Federal Highway Administration (FHWA) defines a tandem as two or more consecutive axles more than 40 inches and not more than 96 inches apart.
• Steer axle: states cannot set the steer axle limit below 20,000 pounds or the manufacturer's rating, whichever is lower.

The Bridge Formula in plain words

The Bridge Formula limits how much weight can sit on axles that are close together, to protect bridges. Congress enacted it in 1975, according to FHWA.

The formula is W = 500 (LN/(N-1) + 12N + 36), rounded to the nearest 500 pounds:

• W is the maximum weight on any group of two or more consecutive axles.
• L is the distance in feet between the outer axles of the group.
• N is the number of axles in the group.

There is also a 36-foot exception: two consecutive tandems can carry 34,000 pounds each if the first and last axles are at least 36 feet apart. In one FHWA worked example, an axle group spaced over 20 feet works out to 51,000 pounds. The truck weight and axle calculator uses the same formula and example.

State differences and permits

FHWA says: "Off the Interstate Highway System, states may set their own commercial vehicle weight standards." Federal rules also protect grandfathered state limits tied to state laws in effect on July 1, 1956, for axles and January 4, 1975, for gross and bridge weights. State permits can allow heavier loads for nondivisible loads. State details are on the truck laws by state page.

What changes a truck's weight

• The tractor: make, sleeper size, engine and fuel load all change the number.
• The trailer: reefers weigh more than dry vans, and steel or combo flatbeds weigh more than aluminum ones.
• Idle reduction units: federal law lets states allow up to 550 extra pounds for an idle-reduction unit (APU) (23 U.S.C. 127).
• Natural gas and battery electric trucks: the same statute allows up to 2,000 extra pounds, with a cap of 82,000 pounds gross.

How truckers check their weight

For how inspections and scales work, see how weigh stations work. To find scales and stations along a route, use the truck stop and weigh station map.

For the curious: a semi vs. a car

An average new passenger vehicle weighs about 4,400 pounds, according to the EPA, for model year 2024, including a 300 pound test allowance. That means a fully loaded 80,000 pound semi weighs about as much as 18 of them.

For more on the trucks themselves, see the history of the 18-wheeler and classic semi trucks every enthusiast should know. Weight limits also come up in the news, as in the New Jersey truck GPS bill on low bridges and weight limits.

More tools are on the trucking tools page.

This guide is general information, not legal advice. Weight rules can change and differ by state, so check the current federal and state rules and the terms of any permit.

FAQ

How much does a semi weigh in tons?

A fully loaded semi can weigh up to 40 tons (80,000 pounds) on the Interstate System, the federal maximum. Empty, a typical sleeper tractor is about 10 tons and a 53-foot dry van is roughly 7 tons, according to the National Academies. These are U.S. short tons of 2,000 pounds, and actual weights vary by build.

How much does a semi weigh without a trailer?

A typical Class 8 sleeper tractor weighs about 20,000 pounds, or 10 tons, according to the National Academies. The number varies by make, sleeper size, engine and fuel load. Day cabs weigh less than sleepers because they have no sleeper berth.

What is the maximum legal weight for a semi?

The federal maximum gross weight on the Interstate System is 80,000 pounds, unless the Bridge Formula sets a lower limit (23 CFR 658.17). Single axles are limited to 20,000 pounds and tandem axles to 34,000 pounds. Off the Interstate, states may set their own standards, and permits can allow heavier nondivisible loads.

How much weight can a semi carry?

Payload equals the maximum legal gross weight minus the tractor weight minus the trailer weight. For a typical sleeper tractor of about 20,000 pounds and a 53-foot dry van of about 14,000 pounds, that leaves about 46,000 pounds, according to the National Academies. Heavier equipment leaves less room for freight.

Why does a semi weigh so much less empty?

Most of a loaded semi's weight can be freight. A typical sleeper tractor and 53-foot dry van together weigh about 34,000 pounds, based on National Academies figures, while the legal maximum is 80,000 pounds. The National Academies puts the maximum payload for that pairing at about 46,000 pounds.

What is a Class 8 truck?

A Class 8 truck has a gross vehicle weight rating of 33,001 pounds or more, according to the U.S. Department of Energy's weight class table. Class 7 covers 26,001 to 33,000 pounds. Class 8 is a rating category, not what the truck actually weighs on a scale.

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