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How to Measure Truck Cab Size (Crew vs Quad vs Extended Cab)

By TruckTon Team · Updated September 2026 · 6 min read

Learning how to measure truck cab size is the step most people skip — and it's the single most common reason a set of running boards shows up and doesn't line up with the doors. Bed length gets all the attention, but when you're buying side steps it's the cab that decides fitment. A board cut for an extended cab leaves a gap under the rear door on a crew cab, and a crew cab board on an extended cab hangs past the rocker where it was never meant to sit.

The good news: figuring out how to measure truck cab size takes five minutes, a tape measure, and no crawling under the truck. This guide covers the three cab types, why every manufacturer calls them something different, the measurement that settles it, and a few shortcuts if you'd rather not measure at all.

Why Cab Size Decides Which Running Boards Fit

A running board spans the cab, from just ahead of the front door to just behind the rear door — a span that changes by a foot or more between an extended cab and a crew cab on the same truck. The mounting brackets matter just as much: they bolt to existing points on the frame and rocker area, and those points move with cab length. Order the wrong configuration and the brackets simply won't reach.

This is why every listing on our side steps collection asks for cab type before year range. Bed length, by contrast, is irrelevant to steps — that's a different measurement, covered in our guide to measuring your truck bed.

The Three Cab Types, Plainly

Strip away the marketing names and modern half-ton pickups come in three cab configurations.

Regular cab — one row of seats, two doors. No rear doors at all. Increasingly rare on dealer lots in Canada, but still common on fleet and work trucks.

Extended cab — four doors, but the rear pair is noticeably shorter. Behind them sits a small bench or jump seats with limited legroom: fine for gear or a short trip, not for adults on a three-hour drive. On some trucks those rear doors are rear-hinged.

Crew cab — four doors of roughly equal length, all front-hinged, with a proper rear bench and real legroom. This is what most Canadian families and work crews buy, and the most common configuration we ship boards for.

That's the whole taxonomy. Everything else is branding.

Every Brand Calls It Something Different

Here's where the confusion comes from. The same physical cab wears a different badge depending on who built it:

Ford — Regular Cab, SuperCab (extended), SuperCrew (crew)
RAM — Regular Cab, Quad Cab (extended), Crew Cab
Chevrolet & GMC — Regular Cab, Double Cab (extended), Crew Cab
Toyota Tacoma — Access Cab (extended), Double Cab (crew)
Toyota Tundra — Double Cab (extended), CrewMax (crew)

Read that list twice and you'll spot the trap: "Double Cab" means extended on a Silverado, Sierra, and Tundra, but crew on a Tacoma — the same two words for two different things inside one showroom. It trips up more buyers than any other naming quirk in the segment.

RAM adds a second variable, having sold the previous-generation body as the "1500 Classic" alongside the current truck. RAM shoppers pick a body style and a cab, which is why our RAM 1500 running board listing separates Classic and New Body Style fitments.

The takeaway: don't shop by name. Shop by measurement.

How to Measure Truck Cab Size in Five Minutes

You need a tape measure and a flat spot to park. Work on the driver's side.

Step 1 — Measure the front door. Run the tape along the bottom edge of the front door, from the shut line at the front to the shut line at the back. Write the number down in inches.

Step 2 — Measure the rear door the same way. Same bottom edge, same shut-line-to-shut-line span.

Step 3 — Compare the two. This is the whole test. Rear door within a couple of inches of the front door: crew cab. Rear door obviously shorter — usually by a foot or more, not subtly: extended cab. No rear door: regular cab.

Step 4 — Measure total cab length. Run the tape along the rocker panel from the front door's leading shut line to the rear shut line of the rear door. That span is roughly what a running board covers — a useful sanity check against a listing's stated length.

Step 5 — Note the year. Trucks get redesigned and brackets move with them, so have the model year handy; most listings split fitments into generation-based year ranges.

Bolt-on aluminum running boards for pickup trucks sized by cab configuration

Three Shortcuts If You'd Rather Not Measure

The tape measure is most reliable, but there are faster ways to confirm what you suspect.

Check the door jamb sticker. Open the driver's door and look at the compliance and tire placard. It carries the VIN and, on many trucks, the model and body designation printed right there.

Run the VIN through the manufacturer. Ford, GM, RAM, and Toyota all offer VIN lookup tools that return the original window sticker or build sheet, spelling out the cab configuration in the factory's own words. This is the definitive answer if you bought used.

Look at the rear door hinges. If the rear doors are rear-hinged — opening backwards, and only once the front door is open — it's an extended cab, full stop.

Matching Your Measurement to a TruckTon Fitment

Once you know your cab, the listing does the rest. Our running boards are built from aircraft-grade aluminum with a 6-inch wide textured step surface, and each model page lists fitments by cab type and year range:

Ford F-150 — Super Crew Cab and Crew or Quad Cab fitments
Chevrolet Silverado 1500 — Crew Cab and Double or Extended Cab fitments
GMC Sierra 1500 — Crew Cab and Double or Extended Cab fitments
Toyota Tacoma — Crew or Double Cab and Quad or Access Cab fitments
Ford Ranger — SuperCrew and SuperCab fitments

Every fitment is $249.99 CAD per set with free shipping Canada-wide. Several ship as pre-orders rather than from stock, so check the listing for current availability and lead time before ordering. Uninstalled items can be returned within 30 days, and everything carries our 2-year warranty.

If your measurement doesn't obviously match a listed option — RAM owners, this is usually you — send us the two door measurements and your VIN first. Shorter conversation than a return.

TruckTon running boards side steps sized correctly for crew cab and extended cab pickups

Common Mistakes We See

Assuming four doors means crew cab. It doesn't. Extended cabs have four doors too. Count doors and you'll guess wrong about half the time; compare door lengths and you'll never guess wrong.

Trusting the used-truck ad. Listings get cab configuration wrong constantly, usually because whoever wrote it counted doors. Verify it yourself.

Mixing up "Double Cab" between brands. Worth repeating: extended on a Silverado, Sierra, and Tundra; crew on a Tacoma.

Forgetting the year range. A 2013 and a 2023 crew cab Silverado are both crew cabs, but the mounting points moved. Cab type alone isn't enough.

Measuring the bed instead. Bed length has nothing to do with step fitment — though it matters enormously for covers, per our F-150 bed sizes guide.

Once You've Ordered

Installation is straightforward on most late-model pickups: brackets bolt to existing frame or rocker points, the board bolts to the brackets, and the job runs one to two hours with hand tools and no drilling. Our step-by-step installation guide walks through it. If wrenching in a cold driveway in February doesn't appeal, we offer free installation with pickup at our Burlington, Ontario location.

Still deciding between styles rather than sizes? Our breakdown of running boards vs nerf bars vs side steps covers which geometry works when the step is buried in slush — and once they're on, a rinse after salty drives is all the upkeep they need, per our seasonal maintenance checklist.