A metal garage should be enclosed on every side, whether each bay gets its own wall and door or the bays share one open interior behind a single wider opening. It is not a shared roofline propped over an open slab. Before you settle on a size, work out how many vehicles need to park inside, what else ends up stored alongside them, and how each bay has to open. Answer those three questions first and the rest of the planning follows on its own.
This is about sizing a garage: vehicles, a workbench, and the equipment that migrates into a garage no matter what it was originally built for. For the full range of sizes and where to start, see our garage and workshop building page. This article is about how to think through your own layout before that first call.
How many bays do you actually need?
Count what you own right now, then count what is coming. A teen driver a couple of years out, a truck that is about to replace a car, a boat or a travel trailer you keep meaning to get out from under a tarp: all of that belongs in the bay count now, not as a surprise addition in three years.
Width matters more than most buyers expect. A single bay is commonly planned at roughly 12 feet wide as a minimum. 14 to 16 feet is more realistic once you want to open both car doors and actually walk around the vehicle, not just park it. Those are typical planning figures, not a fixed rule. Measure your own vehicle before you lock in a number. If you plan to work in the bay and not merely park in it, add more. Multiply that per bay to get a starting width. An extra bay can be added later by lengthening the building, but the width and height can't change once it's built, so settle those now, before the slab is poured and the frame is standing.
What separates a metal garage from a carport with a roof?
A garage has a wall on every side and a door on every opening. A carport, or an open-sided cover on a light tube frame, may close in only one or two sides and leave the rest to the weather. That is a different product, built for a different job. If quotes in a stack look wildly different, check what each one actually includes before you compare them. A four-sided, fully enclosed building and an open-sided cover are not the same purchase, even when both get called a garage.
Size each bay to what has to fit
Work from the vehicle, not the other way around. As a starting point, a single garage door commonly runs about 8 to 9 feet wide and 7 to 8 feet tall. A double door for two vehicles side by side commonly runs around 16 feet wide at a similar height. Those are typical published sizes. Treat them as a starting point and confirm against what you actually own. Before you call an estimator, measure:
- Vehicle width with both doors open, not the vehicle's own width alone
- Vehicle length plus room to walk around the front and the back
- Door width wide enough for the widest vehicle plus its mirrors
- Door height with real clearance above the tallest point, including a roof rack, a raised bed, or an antenna
- Depth left over behind or beside the vehicle for a workbench, shelving, or a walkway
Write these numbers down before you talk to anyone. An estimator can size doors and bays around real measurements in one conversation. Guessed numbers turn into a second conversation later, usually after drawings are already underway.
Door height, eave height and a future lift
Door height and eave height are two different numbers, and mixing them up is one of the more common planning mistakes we hear about after the fact. Door height only has to clear whatever drives through it. Eave height affects the usable clearance inside the bay, but it is not the same as clear ceiling height. Frames, bracing, doors and other overhead components can all cut into the room available, so confirm the actual clearance at those points too, especially if a vehicle lift is anywhere in your plans. A lift needs real room above a raised car, not just enough clearance to park underneath it lowered. A common two-post lift wants roughly 12 to 14 feet of clear ceiling height to raise a vehicle fully; a taller truck or SUV lift often wants more. Those are typical figures from lift manufacturers, so confirm the exact number, and the building's real clear height at that spot, against the lift you plan to buy.
If a lift is even a maybe, say so before you order. Specifying a taller eave up front is a straightforward change on paper. Adding ceiling height after the frame is fabricated is not.
Power, lighting and whether you will heat it
Decide early whether the garage will be conditioned space or unconditioned storage, because that choice changes more than comfort. An unheated garage still needs enough outlets for tools, a garage door opener, and decent lighting over the bench. A heated one needs the insulation assembly planned from the start, not added as an afterthought once the shell is up. Our insulation options guide walks through the real tradeoffs between batt, rigid foam, spray foam, and reflective barrier if conditioning the space is part of the plan.
Leave room on the lot for what comes next
Sizing here does not have to follow a catalog. Northcraft offers any size building the buyer wants, with no size limit, from a modest two-bay garage right now to a much bigger footprint later, if that is ever where this goes. If a second bay or a lean-to along one side is even a maybe, leave the clearance for it on the lot now. Positioning the garage tight against a property line or a septic field trades a few feet of convenience now for an option you might want later.
For a deeper look at sizing method beyond bay counts, see our guide to sizing a steel building. It covers turning radius, growth room, and the other factors that apply beyond a straight garage. And if a single bay with a workbench is genuinely all you need, our 20x24 page shows what that smaller footprint actually fits: one car plus a workbench, not two vehicles.
Frequently asked questions
How big is a two-car metal garage?
Enough width for both vehicles with their doors open and a walkway between them, plus depth for whatever sits behind them. A 30x40 is a common step-up size once a second vehicle, a workbench, and storage all need to share the floor; see our 30x40 page for what fits at that footprint.
What eave height do I need for a car lift?
A common two-post lift wants roughly 12 to 14 feet of clear ceiling height to raise a vehicle fully, and a taller truck or SUV lift often wants more. That is a typical range published by lift manufacturers, not a fixed number, so send your estimator the lift's make and model before you order and let that confirm the real figure.
Should my garage doors be on the endwall or sidewall?
Either can work. The real question is what the door needs to line up with. An endwall door usually gives the straightest pull-through for a long vehicle. A sidewall door can make more sense when several bays need to open independently off one long wall. Tell your estimator how you plan to drive in and out and let the layout follow that.
Can I heat a metal garage?
Yes. A metal garage can be insulated and conditioned like any other steel building, but plan the insulation assembly before you order so the building details can accommodate it. Decide before you order, not after the shell is standing.
Can I add another bay later?
Yes, lengthwise. A building can be lengthened later by adding bays. Its width and height can't be extended, though a lean-to can be added to an existing building. Tell your estimator now if phasing is part of the plan, so the main frame is engineered from the start to carry that future load.
Send us your vehicle list, what else needs to live in the garage, and whether a lift or a second bay is anywhere in the plan. Get a customized quote and an estimator will size the doors and the eave height around your actual answer, not a guess.