What are the Legal Dimensions for a Flatbed?

August 7th, 2025

If you’re in the trucking industry, you’re probably aware of the variety of commercial trailers to choose from when deciding how to transport your cargo. Commercial trailers are available in all shapes, styles, and dimensions to meet various hauling and shipping needs. Apart from dry vans and dump trucks, flatbed trailers are one of the most common choices among owner-operators and fleet managers when moving products from point A to B.

One of the primary reasons flatbeds are so frequently used in the trucking industry is that they are highly versatile. You can load them up from the top, rear, sides, or however you see fit; the only caveat is that there are restrictions on how much freight you can haul per the legal flatbed dimensions.

Read on about the various legal dimensions for a flatbed trailer to ensure you comply with all federal and state laws. Use this guide to avoid costly fines and shipping delays by continuing to operate while following best practices.

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General Legal Flatbed Dimensions

A flatbed trailer’s load must not exceed 8’6” in height, 8’6” in width, and 48’ in length. Its average weight capacity is approximately 45,000 pounds, potentially reaching 80,000 pounds. Specific types of flatbed trailers may have different requirements depending on their design and cargo type, but these are the general guidelines that typically apply.

Different Regulations for Each Type of Flatbed Trailer

Your business is unique, and so is the equipment you use. When abiding by the legal dimensions for a flatbed load, it’s important to know precisely which type of CMV and trailer you’ll be operating, as the rules and regulations vary according to the exact trailer.

Let’s examine each type of commercial flatbed trailer and its corresponding weight and dimension capacity to optimize your freight and load planning. As a rule of thumb, the total weight (truck + trailer + cargo) must be under 80,000 pounds. Heavier trucks, such as sleepers, may affect the cargo weight that can be carried.

Standard Flatbed Trailer Dimensions

A flatbed trailer is meant for transporting goods without an official enclosure (as opposed to dry vans or storage containers). It’s an incredibly popular option within the trucking industry because it’s great for shipping wide or large items that require loading from the side with a forklift or from above using a crane.

Maximum freight dimensions
- Length: 48 – 53 ft.
- Height: 8.5 ft.
- Width: 8.5 ft.
Maximum freight weight
- 48,000 – 52,000 lbs.

Single Drop Flatbed Trailer Dimensions

Single drop deck trailers have a lowered deck to accommodate taller cargo. The bottom and top decks are specifically designed to haul freight that cannot be carried or transported on a standard flatbed, usually due to height restrictions.

Maximum freight dimensions
- Main deck
  - Length: 37 – 43 ft.
  - Height: 10 ft.
  - Width: 8.5 ft.
- Front deck
  - Length: 11 ft.
  - Height: 8.5 ft.
  - Width: 8.5 ft.
Maximum freight weight
- 48,000 – 52,000 lbs.

Double Drop Trailer Dimensions

Double drop trailers are similar to single drop trailers but have a lower main deck and an additional rear deck. This trailer allows you to haul taller cargo up to 11.5 ft. on the main deck, 8.5 ft. on the front deck, and 9 ft. on the rear deck.

Maximum freight dimensions
- Main deck
  - Length: 29 ft.
  - Height: 11.5 ft.
  - Width: 8.5 ft.
- Front deck
  - Length: 10 ft.
  - Height: 8.5 ft.
  - Width: 8.5 ft
- Rear deck
  - Length: 9 ft.
  - Height: 10 ft.
  - Width: 8.5 ft.
Maximum freight weight
- 45,000 lbs.

Extendable Flatbed Dimensions

Extendable flatbeds have nearly identical dimensions to a standard flatbed, but the main deck can be extended to up to 80 ft. in length, depending on the model. The legal dimension of this flatbed is longer than that of traditional trailers.

Maximum freight dimensions
- Length: 48 – 80 ft.
- Height: 8.5 ft.
- Width: 8.5 ft.
Maximum freight weight
- 45,000 lbs.

Single Drop Extendable Flatbed Dimensions

The main deck of a single drop extendable flatbed can be stretched up to 63 feet. These trailers are ideal for hauling loads too long for a standard single-drop flatbed.

Maximum freight dimensions
- Main deck
  - Length: 38 – 61 ft.
  - Height: 10 ft.
  - Width: 8 ft.
- Front deck
  - Length: 10 ft.
  - Height: 8.5 ft.
  - Width: 8 ft.
Maximum freight weight
- 45,000 lbs.

Double Drop Extendable Flatbed Dimensions

Double drop extendable flatbeds have three decks, with an extendable main deck to support longer cargo. This trailer is ideal for hauling unusually long cargo that cannot be carried by a regular double drop trailer.

Maximum freight dimensions
- Main deck
  - Length: 29-50 ft.
  - Height: 11.5 ft.
  - Width: 8.5 ft.
- Front deck
  - Length: 10 ft.
  - Height: 8.5 ft.
  - Width: 8.5 ft.
- Rear deck
  - Length: 9 ft.
  - Height: 10 ft.
  - Width: 8.5 ft.
Maximum freight weight
- 40,000 lbs.

Semi-Trailer Length Laws by State

Federal Size Regulations for Commercial Motor Vehicles

The U.S. Department of Transportation Federal Highway Administration (FHWA) sets the standard for commercial motor vehicles in order to protect the public safety of motorists on the road. Although this post discusses flatbed trailers, remember that a commercial motor vehicle (CMV) refers to any vehicle used to transport goods or passengers for profit. That includes semi-trucks, box trucks, vans, and even buses or taxicabs.

If your business relies on any type of CMV, you must learn all the applicable regulations to comply with federal and state laws. Hale Trailer offers a solution for any commercial trailer rental that fits your needs. Whether your fleet needs dry vans for enclosed transportation or you’re an owner-operator searching for a flatbed trailer rental, we can help.

Contact one of our trailer rental locations and learn the options available for your hauling needs. Our commercial trailer experts will help you find the best trailer that fits your cargo’s height and width according to the current legal flatbed dimensions.