Extended Cab vs Crew Cab: Doors, Rear Seat and Why Running Boards Don't Swap

The short version: crew cab means more room for people, extended cab means less back seat and often more room for bed. Here is how the ARIES cab guide lays it out. ARIES says plainly that its groups are there to help you understand, and that they do not mean the trucks share a design.

One more note from ARIES on extended cabs: the rear doors may only open after the front doors are open. That matters in a tight parking spot, and it matters for where a step sits.

Who calls what: cab names by maker

This is where most of the wrong orders start. A cab name is the maker's choice, and the ARIES table shows how far apart those choices are.

Two things to read out of that table. First, Ford's SuperCab and SuperCrew sit in different groups, so one is not a stand-in for the other. Second, one word, Double, shows up in both columns.

"Double Cab" depends on who built the truck

Do not let anyone hand you one meaning for it. Take it maker by maker.

Chevrolet Silverado and GMC Sierra. ARIES files the Double Cab under extended. Chevrolet's own trucks page lists the Silverado and Silverado HD as Regular Cab, Extended Cab and Crew Cab. So the same cab wears two names, and at least one listing title for 2007-2018 GM trucks uses both in a single line. We did not find a Chevrolet text that describes the rear doors, so look at yours.

Toyota Tacoma. ARIES files the Double Cab under crew. Toyota sells the 2026 Tacoma as XtraCab or Double Cab and lists seating for up to five on the Double Cab only. It describes a fold-flat passenger seat and a lockable rear storage panel on XtraCab models. The ARIES table still shows Access for current trucks, while Toyota and the newer listings say XtraCab. See Tacoma running boards for how the listings split.

Toyota Tundra. This one moved inside one truck line. ARIES puts the 2004-2006 Double Cab under crew and the 2007-to-current Double Cab under extended, with CrewMax taking the crew spot. One 2026 trim summary on Toyota's page shows Double Cab with a 6.5-foot or 8.1-foot bed and CrewMax with a 5.5-foot bed. Tundra running boards covers the CrewMax and Double Cab listings.

How to tell which cab you have

1. Count the doors

   Two doors means a regular cab, or an extended cab with a seat-forward layout. Check for room behind the front seats.

2. Compare front and rear doors

   Rear doors that match the front in size point to a crew-type cab. Clearly smaller rear doors point to an extended-type cab.

3. Open only the rear door

   If it will not open until the front door is open, ARIES describes that as an extended-cab trait.

4. Use the maker's name

   Your window sticker or a dealer can give you the exact cab name. That name is what the listing will use, so match it word for word.

Why boards for one cab don't go on the other

A board bolts to mounting points along the cab, and it has to span the doors it serves. Change the cab and both of those change. Each part is built for specific model years and cabs, sometimes bed lengths.

The clearest numbers we have come from a maker. RealTruck's install guide for the AMP PowerStep 76255-01A, for 2022-up Silverado and Sierra 1500 trucks, uses one board assembly and cuts it by cab: 79 inches for a Crew Cab, trimmed 10 inches to 69 for a Double Cab, trimmed 29 inches to 50 for a Single Cab. That is 10 inches of difference between two cabs on the same truck line.

Listings split the same way. Ram older-body boards come as separate crew and Quad Cab titles. F-150 boards we read name the SuperCrew, so the F-150 page treats the SuperCab as its own question. The Silverado page keeps Crew, Double and Regular apart. On those pages, the fit line shows what each listing states. Check your exact year and cab on the listing before you buy.

Where the bed comes in

Cab-length boards run along the cab, so the bed stays out of it. Wheel-to-wheel boards run from the front wheel to the rear wheel and cost more, according to ARIES, and that ties them to bed length too. Bed and cab fitment walks through how to read those titles.

Beds also vary by cab on the same truck. Ford's 2026 F-150 specs show the Regular Cab with a 6.5-foot or 8-foot box, the SuperCab with a 6.5-foot box and the SuperCrew with a 5.5-foot or 6.5-foot box. Chevrolet lists the Silverado with 5'8", 6'6" and 8'1" beds and the Silverado HD with 6'8" and 8'1", without tying them to a cab on that page.

Which one should you get?

If you are choosing a truck, the call is simple. People ride in the back most days: crew cab. People ride back there now and then, or you want gear locked inside and more bed: extended cab. ARIES adds that crew cabs generally cost more and often give up bed length, and that extended cab back seats are often cramped for taller riders. It also says crew cabs tend to use more fuel; we have no measured figure for that, so we print none.

If you already own the truck, the only question is what is listed for it. Start with your truck below. When you are ready to compare parts across trucks, the best running boards page lists our picks by truck, and how we verify fitment explains what those fit lines are based on.