Posted 11 June 2026 · 8 min read

Carport Sizing Guide: How Big for 1, 2 or 3 Cars (Plus Caravans & EVs)

The most common carport mistake isn't choosing the wrong roof or the wrong colour — it's getting the size wrong. Too small and you're shuffling sideways out of the car door every morning. Here's how to work out exactly how much space you need.

Almost every carport that disappoints does so for the same reason: it's too small. Not catastrophically — it shelters the car, more or less — but it's a few hundred millimetres too tight in one direction, and that few hundred millimetres is the difference between a structure you barely think about and one that mildly annoys you every single day. You clip a wing mirror. You can't open the boot fully. You get rained on in the gap between the car and the edge of the roof.

The good news is that sizing a carport properly isn't complicated. It's just arithmetic that most people skip. This guide walks through the numbers that actually matter — for one car, two cars, three or more, plus the awkward cases like caravans, vans, and electric vehicles that need a charger at the back.

The number most people forget

Here's the mistake. People measure their car, add a bit, and call it the carport size. The car is 1.8 metres wide, so a 2-metre-wide carport will do, right?

No. Because you have to get out of the car, and so does everyone else in it.

A car door needs roughly half a metre to open enough to climb out comfortably — more if you're helping children into seats, loading a wheelchair, or simply not as bendy as you used to be. You need that clearance on both sides if passengers get out, and you want a bit of walk-around space at the front and back for unloading shopping or reaching the boot.

So the real rule is: measure the car, then add clearance on every side you'll actually use. That single adjustment is what separates a carport that feels generous from one that feels like a tin of sardines.

How much space a vehicle actually needs

Vehicles vary enormously, so work from your own car rather than an average. As a rough guide to typical UK vehicles:

Two things people routinely overlook:

• Mirrors add width. Wing mirrors stick out roughly 0.3–0.4m beyond the body on each side. A car that's 1.8m across the body can be 2.1m+ across the mirrors. If you fold them, fine — but plan for the worst case if you don't.
• Length is bumper-to-bumper, not where you park. People rarely pull right up to a wall. Leave a margin at the front and a margin at the back so you're not playing millimetre games every time you arrive home tired.

The honest takeaway: measure your actual vehicle (the manufacturer's spec sheet lists length and width), add door clearance to the sides and a walk-around margin front and back, and that is the footprint your carport needs to cover.

Sizing for one car

For a single vehicle with comfortable access, you're generally looking at:

• Around 3 metres across the opening — enough for the car plus a door's worth of clearance on the access side.
• Around 5 metres of cover front-to-back for most family cars, so the vehicle sits fully under the roof with a margin at each end.

A 3m × 5m single carport size suits the vast majority of cars on UK driveways. If you've got a larger SUV, want generous door clearance on both sides, or like to potter around the car under cover, size up rather than down — you won't regret the extra space, and you'll never wish you'd made it smaller.

Sizing for two cars, side by side

This is where the "add clearance on every side you use" rule really bites, because now you've got a door-opening gap in the middle as well as the outsides.

• Around 5.5 to 6 metres across is the practical minimum for two cars parked side by side — that's two vehicles plus enough room to open the inner doors without a door-edge handshake.
• Around 5 metres of cover front-to-back, as for a single car.

Six metres of width is the comfortable two-car number, so if you're searching for double carport dimensions, that's your target. Anything tighter and someone's always climbing across the gearstick. Our British-made Harbour carport spans up to 12 metres wide in a single structure, so a roomy two-car (and even three-car) layout is well within its range without any awkward compromises.

Sizing for three or more cars

For three vehicles side by side you're looking at roughly 8.5 to 9 metres of width — three car widths plus the door gaps between them. Beyond that, a fourth vehicle pushes you toward 11–12 metres.

At this scale, freestanding is usually the answer (you rarely have that much unbroken house wall to attach to), and the structure needs intermediate support posts. The Harbour carries up to 5 metres between posts, so a wide multi-car span is handled with a sensible number of uprights rather than a forest of them.

If you need to cover a long driveway or several vehicles and want to keep costs down, the modular Portico is worth a look: individual units cap at 6m × 3.5m, but they're designed to be combined end-to-end or side-by-side into one continuous run, so there's no practical limit on the overall size.

The awkward cases

Caravans, motorhomes and boats

These need real thought, because they're both longer and taller than cars.

• A touring caravan body is often 5 to 7+ metres long, and once you factor in the towing A-frame and the car in front, the parked footprint is long indeed. UK towing width tops out at 2.55m, so width is less of an issue than sheer length and height.
• Motorhomes commonly run 6 to 8 metres or more.

For these, depth (how far the structure projects) and height clearance matter more than width. Measure the full height of the unit including any roof vents, aerials or air-conditioning units, and make sure the carport's clearance comfortably exceeds it. If you're sheltering a caravan and the towing vehicle, plan for the combined length — or accept that the drawbar will sit outside the cover.

Electric vehicles

If you're charging an EV under the carport — and a covered, well-ventilated carport is one of the best places for a wallbox — you need room for the charger and cable at the rear, not just the car.

That means extra depth. We'd recommend at least 6 metres front-to-back so the vehicle sits fully under cover with the wallbox mounted on the back wall or post and the cable reaching the charge port without stretching. The Harbour configures up to 6 metres deep, which makes it the natural choice if EV charging is on your list; the Portico's 3.5m maximum depth can be tight once you add a charger behind the car, so it's worth flagging early.

Vans and roof boxes — don't forget height

Height is the dimension that catches people out. A standard car needs little headroom, but a panel van, a 4x4 with a roof box, or a vehicle with roof bars and a kayak on top needs a good deal more.

Measure the tallest thing that will park there, including anything on the roof, and add clearance. It's also worth knowing the planning rules here: carports usually fall under Permitted Development provided they stay within 2.5m eaves height (if within 2m of a boundary) and 4m overall for a pitched roof, or 3m for a flat roof. There's usually plenty of room for a van within that — but it's a constraint worth checking before you design around a high vehicle. (Our full planning permission guide covers the detail.)

Attached vs freestanding changes the maths

One last thing that affects usable space: how the carport is mounted.

• Attached (wall-mounted) carports fix to the house on one side, so there are no posts along that edge — you get the full width to use. Ideal when the drive runs alongside the house.
• Freestanding carports stand on their own posts on all sides. They go anywhere on the plot, but the corner posts sit inside the overall footprint, so allow for them when you're planning door clearance near the edges.

Both the Harbour and the Portico can be configured either way. Which suits you depends on your driveway layout, not just the number of cars — and it's exactly the kind of thing we work out with you during design.

So, which size do you need?

The short version:

• One car: around 3m × 5m for comfortable everyday use.
• Two cars: around 6m × 5m so nobody's squeezing past in the middle.
• Three cars: around 8.5–9m wide.
• Caravan / motorhome / EV: prioritise depth and height, not just width.

And the honest version: every driveway is different, every vehicle is different, and the right answer depends on how you actually use the space — whether you load kids and shopping daily, whether the mirrors fold, whether there's a charger or a caravan in the mix. We measure all of that properly before quoting, so the carport fits your life rather than a generic template.

Frequently Asked Questions