How to Measure a Truck Sleeper Cab for a Mattress

By the Nomad Mattress Sleep Team · Last updated: October 2, 2026

Table of Contents

• Tools You Need Before You Measure
• How to Measure Your Sleeper Cab: Step-by-Step
• Truck Mattress Size Guide: What Your Measurements Mean
• Corners, Tapered Edges, and Obstructions
• Platform Structure and Weight
• How to Avoid Gaps in a Sleeper Bunk
• Factory (OEM) Mattress vs. Nomad Truck Mattress
• Frequently Asked Questions

Tools You Need Before You Measure

A tape measure is the one tool you can’t skip; a notepad and a helper just improve accuracy.

• Tape measure: a 5-metre (16 ft) retractable tape is enough for any sleeper bunk
• Notepad or phone: record every number as you take it, in inches and centimetres
• Flashlight: bunk corners and under-frame gaps hide in shadow
• Pencil: mark the bunk frame edge so you measure from the same reference point twice

How to Measure Your Sleeper Cab: Step-by-Step

Measuring a sleeper cab means capturing three numbers: length, width, and height, each taken at the bunk itself rather than the cab walls.

Step 1: Remove the Old Mattress and Clear the Bunk

Pull the mattress out completely. A mattress left in place hides the bunk frame edges, the lip where the platform meets the cab wall, and any hardware that eats into usable space. Clear off bedding, bins, and loose gear.

Step 2: Measure Length and Width

Run the tape from head wall to foot wall at bunk level, not mattress-top level. Cab panels curve inward as they rise, so a higher measurement reads short.

Take the width at both the head and the foot. Many sleeper bunks taper, and a mattress sized to the wider end will bind. Write down the narrower number.

Step 3: Check Height and Clearance

Measure from the bunk surface to the lowest point overhead, often the bunk window frame or a storage cabinet, not the ceiling. This sets your maximum mattress thickness. If you have an upper bunk, measure the clearance with it folded down.

Truck Mattress Size Guide: What Your Measurements Mean

Most sleeper bunks are 80 inches long, and the width depends on the truck and cab. Match your narrowest width to the closest size without going over:

Reading Your Numbers

Round down, not up. Foam compresses a little; it does not stretch. A bunk measuring 38″ at its narrowest takes the 36″ mattress, not the 39″. A bunk that measures 152 cm at the head and 147 cm at the foot is a 147 cm bunk for fit.

When Your Measurements Fall Between Sizes

“Standard” sleeper dimensions vary by truck model year and cab configuration, so trust your tape measure over the spec sheet. If your bunk is shorter than 80 inches, or falls well between two widths, email customercare@nomad-mattress.com with your measurements and a photo before you order, and we’ll help you choose.

Height and Thickness: The Number Drivers Forget

Floor-to-ceiling height determines how thick a mattress you can use and how much sitting room is left. The Nomad Truck Mattress is 7 inches (18 cm) thick, so check that your clearance leaves enough room to sit up comfortably once it’s in. Measure to the lowest overhead obstruction, such as a bunk window, cabinet door, or reading light, not the ceiling.

Corners, Tapered Edges, and Obstructions

Nomad Truck mattresses are made in the standard rectangular sizes above. If your bunk isn’t a perfect rectangle:

• Rounded corners: measure length and width along the straight edges, between the points where each curve begins.
• Tapered foot end: size to the narrowest width.
• Obstructions such as wheel arches, access panels, seatbelt mounts, overhanging cabinets, or heater ducts: note how far each one sticks into the bunk and send us a photo before ordering.

Platform Structure and Weight

Check the bunk platform before ordering: press down firmly at the centre and each corner. A platform that flexes under hand pressure will flex more under a body. If gas struts hold the platform up for storage, make sure they still hold it open; a heavy mattress can overwhelm weak struts.

Weight also matters for payload. Nomad Truck mattresses are built light, so you get full support without adding unnecessary weight to the cab.

How to Avoid Gaps in a Sleeper Bunk

Gaps come from three sources: a mattress sized to the wrong end of a tapered bunk, a mattress that’s too long or wide and buckles, or obstructions the mattress sits on top of. Measure at the narrowest point, round down, and check for obstructions first. The Nomad Truck’s reinforced transfer edge also keeps the sides firm, so the mattress holds its shape against the bunk walls and doesn’t slump when you sit on the edge.

Factory (OEM) Mattress vs. Nomad Truck Mattress

If you’re replacing a factory mattress, measure the bunk rather than the old mattress. The original may have been undersized from day one.

Getting the measurements right is the hard part. The Nomad Truck Mattress is made in Canada in the four most common sleeper widths, with Thermo-Adaptive foam for every season, free shipping to most areas in Canada, a 90-night sleep trial and a 20-year limited warranty.