Semi-trucks are some impressive machines. In fact, their prevalence and size ensure that no one ever questions their impressiveness. Sometimes called 18-wheelers or big rigs, these tractor trailers take up major space on the road. Anyone who has ever driven next to a large truck has witnessed their sheer mass – in length, width, height, and, not as obviously, in weight, as well.

These monstrous vehicles are indeed as big as they appear while cruising on the freeway. While we’ll get into the nitty gritty details in a moment, we’ve done the math to come up with a basic estimate of just how big these beasts of the road can get.

The average tractor-trailer is 72 feet long, 12 feet long, 13.5 feet tall, and can weigh up to 80,000 pounds. 

These specs are for a laden trailer hauled by a tractor with a day cab, but so many different things determine the dimensions of semi-trucks. Let’s take a look at the different measurements that go into calculating the size of a semi.

How Much does a Semi Truck Weigh?

There are two different measurements you can collect when weighing a semi-truck.

• Laden weight. Weigh the tractor and the trailer when the trailer is fully loaded. This is heavily influenced by the weight of the load that the truck is carrying. This can also be referred to as gross vehicle weight, or gross vehicle weight rating (GVWR).

• Unladen weight. Weighing just the tractor and trailer when the trailer is empty. 

A truck’s weight depends on many things besides the weight of its load. For example, a single truck tire typically weighs more than 100 pounds on its own. When you multiply that by 18, you get…a ton (literally) of weight. Whether or not the cab is a sleeper or not also adds some weight, as does the type of trailer it carries (e.g. flatbed or reefer), and what engine it has.

A semi-tractor can weigh anywhere from 10,000-35,000 pounds, and an empty, 53-foot trailer weighs about 10,000 pounds. Unladen, that can be up to 35,000 pounds…and we haven’t even added in cargo weight yet!

According to federal and Utah state laws, a semi-truck can have a gross vehicle weight rating of up to 80,000 pounds and still be permitted on the road. Semis are the heaviest things on the road, alright! And the DoT knows it.

How Long is a Semi Truck?

In addition to weighing a lot, it’s obvious that semis take up a lot of space on the road, as well. These are massive vehicles, and with five axles, they can rack up the footage to upwards of 70 feet. Its length is typically measured from the middle of the rear wheel to the center of the steer.

Trailers are 53 feet long. This is a federally regulated minimum length (although, according to those same regulations, there is a grandfathered rule that the minimum length a trailer can be is technically 48 feet long). States can increase lengths independently. For example, Utah allows trailers up to 57 feet, although you do need an LCV, or long combination vehicle, permit to drive them.

That LCV permit also allows you to pull multiple trailers at once, which will, of course, add to the length of your truck. Multiple trailers can mean two, or even three, trailers behind a single tractor. If you’re doing the math along with us, yes, that’s over 100 feet of just one truck. 

To figure out the total length of a tractor-trailer, you add the trailers it’s hauling to the length of its cab. Day cabs, or cabs without bed space, can be around 20 feet long. Long days on the road can sometimes warrant naps and resting space, so sleeper cabs can be closer to 30 feet long to accommodate a bed and some more square footage dedicated toward living and storage.

A standard semi with a day cab is around 72 feet long…meaning that drivers must know how to confidently drive and park these vehicles and helps non-drivers understand why there are so many warnings on trucks about them making wide turns! Keep in mind that since sleeper cars are even longer than this, sometimes a tractor that’s hauling a single trailer can end up being over 80 feet long.

How Wide Is a Semi Truck?

While the length of semi-trucks can vary by a few feet, and their weight can vary by tons, semi-truck widths are fairly standardized. 

Trailers are typically around eight feet wide, sometimes spanning up to eight and a half feet. Semi-cabs are a similar width. This allows them to fit on a standard highway lane in the U.S., which is typically around 12 feet wide, while still leaving some wiggle room. 

How Tall Is a Semi Truck?

In addition to their impressive length and width, semi trucks can be around 13.5 feet tall, allowing them to clear many tunnels and other height limits while out on the road.

For context, tall SUVs are around six feet tall. This sounds positively miniature when compared to the monstrosity that is an 18-wheeler.

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If you’re interested in learning all the specifics of semi trucks, consider Driving with Pride Transport. Over the past 40 years, we have witnessed size regulations change and equipment improve, and we’re eager to keep our fleet as up-to-date and comfortable as we can. We’re looking for drivers who want to be part of our family and strive to uphold our top tenets of safety and knowledge. If you fit the bill and know the ins and outs of semis (or want to know about them), take a look at our current list of job postings.