What Size Tonneau Cover Do I Need?

On this page (7 sections)

1. How do I measure my truck bed for a tonneau cover?
2. Which truck details matter besides bed length?
3. Why do F-150 covers come in different lengths?
4. How do bed features change cover fit?
5. What if the measurement falls between two listed sizes?
6. What should I confirm before buying a tonneau cover?
7. What size tonneau cover do I need for my truck?

Match a tonneau cover to your exact truck, bed length, and bed features. Measure the inside bed length, then confirm the model year, body style, and options such as RamBox before choosing a cover.

Truck makers use several bed lengths within the same model line. A cover that fits one F-150 or Ram 1500 bed may be too short or too long for another.

How do I measure my truck bed for a tonneau cover?

Measure from the inside front wall of the bed to the inside edge of the closed tailgate. Keep the tape straight along the bed floor and write down the measurement in inches.

Use the measurement as a fit check, not the only identifier. Truck makers and cover brands may describe a bed by a rounded foot length, a precise inch measurement, or a named configuration.

Measure twice, using the same endpoints each time. If the result is far from the bed length you expected, check that the tape is straight and that you haven't measured the outside of the truck.

A 25-foot tape measure is long enough for this job and has fractions printed on the blade for reading between whole inches.

Don't measure the truck's overall length or the open tailgate as extra bed space. A tonneau cover is made for the bed opening and its rails, so measurements outside that area won't identify the right fit.

Which truck details matter besides bed length?

Check the model year, body style, bed configuration, and special features. These details can separate covers that share a truck name but fit different beds.

Write down the truck's:

• Make, model, and model year
• Bed length in inches and the truck maker's bed name
• Body style, such as Styleside or Fleetside
• Bed rail or cargo system details that affect mounting
• Features such as RamBox

Check the owner's manual, vehicle documents, or the truck maker's fit guide if you're unsure of the configuration. A door-jamb label can help identify the truck, but it may not spell out the bed details you need.

Start with our truck bed cover styles guide if you're also deciding between a soft roll-up, folding, or other cover style. Fit comes first: a style you like still needs to match the bed.

Why do F-150 covers come in different lengths?

F-150 covers vary by bed length and bed style, so confirm both before you choose. The two MOSTPLUS options here are for Styleside F-150 beds, one sized for 5.5 ft and the other for 6.5 ft.

The 5.5 ft option is specified for 2015–2026 F-150 Styleside beds and gives a 67-inch bed length. The 6.5 ft option is specified for 2015–2026 F-150 Styleside beds and is described as 78 inches.

The different lengths aren't interchangeable. Compare your truck's bed measurement and body style with the fit details for the exact cover.

If you drive a Silverado 1500, the Silverado bed sizes and fit guide covers its bed options. For other model-specific questions, check the guides to Ram 1500 bed lengths and fit and Toyota Tundra years, beds, and rails.

How do bed features change cover fit?

A feature such as RamBox can change which cover fits, even when the bed length matches. Confirm those details before focusing on the cover's style or fold count.

The MOSTPLUS 5.7 ft Ram 1500 cover is specified for 2009–2026 Ram 1500 models without RamBox and for a 5.7 ft bed measuring 67.4 inches. Its compatibility also distinguishes Ram 1500 Classic and New Body model years.

That fit note is a reminder to check the whole truck configuration. Don't assume that a cover for one Ram 1500 bed also fits a RamBox bed or another bed length.

Rails and other bed-mounted accessories may affect installation too. If you plan to add a rack, see what works with a tonneau cover and bed rack before choosing a setup.

What if the measurement falls between two listed sizes?

Don't choose the nearest size by guesswork. Recheck your endpoints, then use the fit guide for your exact truck and compare the cover's stated bed length and configuration.

Truck bed labels can be rounded. A product described as 5.5 ft may also give a precise inch figure, so compare the truck's stated bed length and the cover's fit details rather than relying on the rounded label alone.

If your truck's measurement still doesn't line up, check the vehicle manual or ask the cover maker to confirm fit for your year, body style, and bed features. Avoid ordering until the fit is clear.

What should I confirm before buying a tonneau cover?

Confirm the truck details and cover fit together in one final check. This helps catch a wrong bed length or configuration before installation.

Use this checklist:

1. Confirm make, model, and model year.
2. Identify bed length and body style.
3. Measure the bed opening in inches.
4. Check features such as RamBox and bed rail systems.
5. Match every detail to the cover's fit information.

A cover that sits unevenly, leaves a gap, or won't latch may need adjustment, but a mismatch in bed size calls for the correct cover. Our guide to adjusting a tonneau cover that sags or rattles explains common adjustment checks.

What size tonneau cover do I need for my truck?

You need the cover specified for your truck's model year, bed length, body style, and bed features. Measure the inside bed length, then confirm the precise fit before choosing a cover style.

For an F-150, compare 5.5 ft and 6.5 ft fitments carefully. For a Ram 1500, check the bed length and whether the truck has RamBox.

If the details don't match, pause and verify fit with the truck's manual or the cover maker.

After the fit is settled, compare truck bed cover styles to choose a design that suits how you use the bed.

Frequently asked questions

How do I know what size tonneau cover to buy?

Match the cover to your truck's make, model year, bed length, and bed features. Measure the inside bed length from the front wall to the tailgate, then check whether the cover fit is for your body style and options such as RamBox.

Use the truck's manual or manufacturer fit guide if details are unclear.

Do I measure a truck bed with the tailgate up or down?

Measure from the inside front wall of the bed to the inside edge of the closed tailgate, keeping the tape straight along the bed floor. If the tailgate is open, use the same endpoints and note that your measurement is an approximate fit check.

Confirm the truck's stated bed length before ordering.

Are 5.5-foot and 6.5-foot covers interchangeable?

No. A cover made for a 5.5-foot bed is not a substitute for one made for a 6.5-foot bed.

Those lengths describe different fitments, even when the truck model is the same.

Check the fit for your exact bed and body style, then confirm the listed inches against your measurement.

Does a tonneau cover fit every trim of the same truck?

Not always. Bed length, body style, bed rails, and options can change fit.

For example, a cover may fit a Styleside bed but not another bed configuration, or require a truck without RamBox.

Verify those details against a fit guide for your truck before choosing.