How to Measure Your Truck Bed for a Tonneau Cover (Bed Length Chart by Truck)

To measure your truck bed for a tonneau cover, run a tape measure along the bed floor from the inside of the front wall (the bulkhead) to the inside of the closed tailgate. Then match that number to your truck's nominal bed size, like 5.5 ft, 6.5 ft or 8 ft.

That second step matters more than most people think. Tonneau covers are sold by make, model year and nominal bed size, not by exact inches. Your tape measure's real job is to confirm which bed you have, so you order the right part number the first time.

It takes about five minutes. Below you'll find the step-by-step method, a bed length chart for 15 popular pickups, and the measuring mistakes that cause most wrong-size orders. Once you know your size, our guide to the best tonneau covers shows the top picks for every bed.

The Measurements That Actually Matter

Inside bed length is the only number every cover needs. The other checks below catch the fitment problems that a length number alone misses.

Tools You Need

A 25 ft tape measure is enough for any pickup bed. A second person helps hold the tape flat, but you can hook the tape on the tailgate and work alone.

• Tape measure (25 ft, with a hook end)

• Notepad or phone to write down each number

• Your truck's VIN or window sticker to confirm the exact model year, cab and bed configuration

• Flashlight (optional) for reading the tape near the bulkhead

How to Measure Your Truck Bed, Step by Step

Measure with the tailgate closed and the bed empty. The whole job takes about five minutes.

1. Park on level ground and close the tailgate. An open or half-latched tailgate adds inches and gives you a wrong number.

2. Empty the bed. Remove loose mats, tool bags and anything leaning against the bulkhead.

3. Hook the tape on the inside of the closed tailgate. Run it along the side of the bed, just below the top of the bed rail, where the cover will sit.

4. Read the number at the inside face of the bulkhead. Keep the tape straight and tight; a sagging tape reads long.

5. Repeat on the other side and in the middle. The three readings should agree within about half an inch. If one is far off, re-measure that side.

6. Write down the result in inches. Round to the nearest half inch.

7. Match it to the chart below. Find your truck and model year, then pick the nominal bed size closest to your number.

8. Confirm with your paperwork. Your window sticker, build sheet or a VIN decoder lists the bed length the factory used. When your tape and your paperwork agree, you know which cover to order.

Truck Bed Length Chart by Truck

Find your truck, then match your tape measure reading to the closest inside length below. Inside lengths are approximate factory figures; your own reading may differ by an inch or so.

Why Your Bed's Size Name Matters More Than Your Tape Measure

Truck makers name beds with rounded sizes, and cover makers build to those names. A bed sold as "5.5 ft" rarely measures exactly 66 inches; it is usually an inch or so longer. That gap is normal, and it is why you match your number to the nearest nominal size instead of searching for an exact inch.

The nominal size is only half of the fit. Cover makers design each model around a specific make, model year range and bed size, because rail shapes, tailgates and bed features change between truck generations. Two beds with nearly the same length can need different covers.

So when you shop, filter by all three: make and model, model year, and nominal bed size. Cab style (regular, extended, crew) doesn't decide the cover by itself, but it limits which bed lengths your truck could have.

How Cover Makers List Bed Sizes

Cover listings describe your bed in one of three ways, and all three point to the same thing.

• By nominal name: "5.5 ft bed", "5'7" bed" or "short bed".

• By inches: "67.1 in bed", usually the factory inside length, rounded.

• By truck and years: "Fits 2019–2026 Silverado 1500, 5'10" bed".

Each combination of truck, year range and bed length gets its own part number. The same cover model is sold under different part numbers for a 5.5 ft and a 6.5 ft F-150 bed, so the model name alone is never enough.

Before you buy, check three lines on the listing: the model years, the bed length, and any exclusions, such as "not compatible with the factory bed rail system" or "will not fit RamBox". If one of the three doesn't match your truck, keep looking. On Amazon, add your truck to Amazon Garage, the site's vehicle fit checker, to see whether a cover matches your make, model and bed length.

Common Measuring Mistakes That Lead to Wrong Covers

Most wrong-size orders come from one of these six mistakes, not from a bad tape measure.

• Measuring with the tailgate open or unlatched. You'll read several inches long. Always measure to the inside of a fully closed tailgate.

• Measuring the outside of the bed. Covers fit inside the bed rails, so outside measurements over the bumper or rail caps don't apply.

• Ordering by cab size. "Crew cab" doesn't tell a cover maker your bed length; many crew cabs come with two bed options.

• Ignoring the model year. A cover for one truck generation may not fit the next, even when the bed length is the same.

• Forgetting factory bed features. Built-in rail tracks, in-bed storage boxes and special tailgates can need a specific cover version or an adapter.

• Trusting one reading. Measure both sides and the middle; a single sagging tape is the most common source of a wrong number.

Special Cases: Liners, Rail Systems, Tool Boxes and Utility Beds

Your bed length can be right and the cover can still fail to fit. Check these four cases before you order.

• Bed liners. Spray-in liners don't affect fit. Drop-in liners come in under-rail and over-rail styles; many covers only work with under-rail liners, so check the cover's listing before you buy.

• Factory rail and cargo systems. Several trucks have built-in rail tracks or in-bed storage boxes. Many covers are made in a version for these beds, or include an adapter; the product's fitment notes will say.

• Crossover tool boxes. A box that sits across the front of the bed shortens the space a cover can use. You'll need a shortened "toolbox" version of the cover; see tonneau covers that work with a tool box.

• Utility and service beds. Standard tonneau covers are built for factory pickup beds, so most won't fit a service body. See tonneau covers for utility beds for the options that do.

Measuring for a Tool Box Under a Tonneau Cover

If you want a tool box or storage box under a closed cover, you need one more number: usable height.

1. Measure from the bed floor straight up to the top of the bed rail, at the spot where the box will sit.

2. Subtract the space the cover's frame takes below the rail. Many covers clamp side rails just under the bed rail, which lowers the clearance. The cover maker's spec sheet or install guide lists it.

3. Leave about half an inch of gap so the box doesn't rub the cover over bumps.

4. Measure the box's footprint too: the width between the wheel wells and the front-to-back space you'll give up.

The result is the tallest box you can carry with the cover shut. For low-profile options, see tool boxes that fit under a tonneau cover.

You've Measured. Here's What to Do Next

With your bed size and model year confirmed, you're ready to pick a cover.

• Find covers for your exact truck: browse tonneau covers by truck for fitment tables and picks for each model.

• Not sure which style you want? Start with our best tonneau covers for pickup trucks and the hard vs soft tonneau cover comparison.

• Ready to install? Our installation guide walks through clamp-on covers that need no drilling.