How To Measure a Truck Bed

January 12, 2024January 10, 2024 Bruce Lindermann 0 Comments TrailFX, Truck Accessories, Truck Bed

What makes a pickup truck a pickup truck? No, we’re not looking for some inspired hypothetical answer– It’s the bed. No pickup truck can wear the title without one, and it’s how you use that bed that defines your truck.

There’s no shortage of things to do with a pickup truck, either. You can outfit it with tonneau covers, bed liners, tool boxes, roll bars, spare tires, tents, and on and on and on. While parts lookups may do most of the work for you, many of those parts aren’t guaranteed to fit without you taking a few simple measurements prior to selecting them.

There’s nothing more frustrating than waiting for new, expensive parts to show up only for you to find that they don’t fit – especially if you’re stuck with any kind of return fees. Luckily, all you need to avoid that is a tape measure, and we’re happy to teach you how to use it.

Measuring for Most Accessories

Before getting started, you should know that getting in ‘the general range’ is usually enough for most truck accessories. The fact of the matter is that most people who are making upgrades to their truck beds are working with made-to-fit parts. Tonneau covers, bed mats, and bed rugs are all common items that are generally made to fit the specific bed of your specific truck. In these instances, the only measurement you need to take is the length of the bed, since most truck models are offered in multiple bed lengths.

Taking the bed length measurement is simple. The first step is to make sure your truck is parked on level ground in a well-lit area. Next, run your tape measure from front to rear and measure the inside length of the bed with the tailgate closed. You can use the top of the bulkhead and tailgate for convenience, but be sure to take note of their respective lengths and subtract them from your measurement.

You don’t need to be super critical here. Manufacturers tend to squeeze in an extra fraction of an inch when providing specs on bed sizes. As long as you’re in the ballpark with size and you know the year of the truck, you should be fine.

What About Step Sides?

Depending on the year and make of your truck, the parts lookup might prompt you with the question of whether your truck is a step-side or a flare-side. And though the length is all you need for most cases, this detail can change everything.

Either of those truck bed styles is defined by the placement of the wheel wells on the outside of the bed rails. But rather than moving the wheel wells outward, the bed rails are moved further inward, making the interior width of the bed much shorter than a traditional model’s.

This, along with other factory options that alter the bed’s dimensions – such as RAMboxes – will play a direct role in determining what part numbers are meant to work with your truck. You won’t need to know their specific dimensional impact with made-to-order parts, though. You simply need to take note of their presence and make sure to select parts that are made to work with the length of bed your truck has, with or without those accessories.

Taking it a Step Further

Things get a little trickier when moving away from made-to-fit parts. A lot of aftermarket parts are made at predetermined dimensions. Even though there’s no universal standard set in place for truck manufacturers to adhere to when selecting bed sizes, they seem to fall within a set range that makes it possible for general sizing to work.

Truck crossover toolboxes are a great example of this. They fit between the bed side rails with a portion extending over the top as though it were made for whatever truck it’s mounted in when it’s actually universal. The only reason it fits so well is because the owner or installer took the time to get the right measurements.

The measurements you need to take are largely determined by the part or parts you’re installing to the bed. Below is a list of some measurements you may need to take while selecting aftermarket parts to mount to your truck.

Bed Width

Bed width should be taken by running a measuring tape from side to side on the bed. If the part you’re measuring for sits down inside the bed, then only concern yourself with the distance between the bed rails. Parts that sit on top and between the bed rails, like crossover toolboxes, require you to also take a measurement of the width with the tops of the bed rails factored in.

Bed Depth

Bed depth is the distance between the top of the bed side and the bottom of the bed. This measurement is important for selecting parts like tool boxes that you want to sit below the bed rails. If you’re measuring for a truck that will feature a tonneau cover, you will also want to factor in any space taken up by the cover to prevent the two from interfering with one another.

Wheel Well Height and Location

Wheel well placement can interfere with a number of aftermarket accessories, with some even being built to fit around them. If you have any parts mounting inside the bed, like wheel well tool boxes, you’ll need a measurement of the distance between the wheel well and the bedside rail to ensure the proper fit. Distance between the wheel wells and from the bulkhead or tailgate can also be helpful when building custom parts or systems for the truck.

Bed Side Rails and Stake Pockets

Parts rarely mount to the top of the bed, but there are a few examples out there. Bed side rail length can be taken by simply running a tape measure along it from front to rear. Though, stake pockets are generally used as the mounting points, and the measurement between the two is all you need to determine what works in these instances.