Picking the wrong size is the single most common mistake people make when buying a metal garage. They measure their vehicles, order a building that fits them — and then realize there is no room to open the doors, walk around, or store anything else.

Sizing a metal garage properly takes about 15 minutes of planning. Do it right and you will have a building you love for decades. Skip it and you will be wishing you had gone bigger within the first year.

Here is exactly how to do it.

Start With What You Are Parking

The first step is simple: list every vehicle or piece of equipment you plan to store. Do not just think about what you have today — think about what you might have in two or three years.

Here are typical vehicle footprints to work from:

• Standard car or sedan: 6 ft wide × 16 ft long
• Full-size pickup truck: 7–8 ft wide × 20–22 ft long
• Large pickup (dually or long bed): 8 ft wide × 22–24 ft long
• SUV or minivan: 7 ft wide × 17–19 ft long
• Boat on trailer: 8–10 ft wide × 20–30 ft long (varies widely)
• RV or motorhome: 8–10 ft wide × 30–45 ft long
• Riding mower or ATV: 4–6 ft wide × 6–8 ft long

Write down every item. Add them up. That gives you your minimum floor space — but you are not done yet.

Add Clearance — This Is Where Most People Go Wrong

Your vehicles' footprints are not your garage size. You need working clearance around every vehicle so you can actually use the space.

Side clearance: Plan for at least 2–3 feet on each side of a vehicle. This lets you open doors fully, walk around comfortably, and work on the vehicle without bumping into a wall. If you plan to do any mechanical work, go 4 feet on the driver's side at minimum.

Front and rear clearance: Leave 3–4 feet at the front and rear of each vehicle. You need room to walk in front, access the engine bay, and maneuver when pulling in and out.

Between vehicles: If you are parking two vehicles side by side, add at least 2 feet between them so both driver's doors can open.

A practical example: A single full-size pickup truck is 8 ft wide × 22 ft long. Add 3 ft on each side (6 ft total) and 4 ft front and rear (8 ft total). That puts you at a minimum of 14 ft wide × 30 ft long just for one truck with comfortable clearance. Most people order a 20×30 or 20×35 for a single truck garage, and they are glad they did.

Choose the Right Door Size

Your roll-up door needs to be wider and taller than your vehicle — not just barely, but comfortably.

Door width: Add at least 2 feet to your vehicle's width. A standard pickup truck at 8 ft wide needs at least a 10-foot door. A 12-foot door is even better and gives you room to pull in without white-knuckling it every time.

Door height: Standard vehicles fit through a 7-foot door, but most people regret not going taller. If you have a lifted truck, a truck with a roof rack, an RV, or a boat on a trailer, you may need a 9-foot, 10-foot, or even 12-foot door. Measure your tallest vehicle at its highest point and add at least 12 inches of clearance.

Number of doors: If you are parking two vehicles side by side, you have two options — one wide door (18 ft or 20 ft) or two separate doors. Two separate doors give you more flexibility and better insulation. One wide door is easier to pull through if you are not great at judging width.

Account for Storage and Work Space

Most people want their garage to do more than just park vehicles. If you plan to use any of the following, you need to add square footage:

• Workbench along one wall: Add 3–4 feet of depth to that wall
• Tool storage, shelving, or cabinets: Add 2–3 feet per wall you plan to line
• Lawn equipment (mowers, blowers, trimmers): Add a dedicated zone of at least 8×10 ft
• Motorcycle or ATV storage: Add 4×8 ft per unit
• Freezer or refrigerator: Small footprint but needs a dedicated wall outlet and space
• Tire storage: Tires take up more room than you think — plan for a rack

A good rule of thumb: if you want a functional workspace in addition to vehicle storage, add at least 10 feet to the length of your building. A two-car garage that is 24×30 becomes a much more useful 24×40 once you factor in a workbench and storage wall.

Think About Height (Leg Height)

Leg height — the height of the sidewalls — affects how usable your garage feels inside and what you can store.

• 10-foot legs: The minimum most people should order. Feels open, works for standard vehicles and most storage needs.
• 12-foot legs: Recommended for lifted trucks, boats on trailers, or anyone who wants to install a car lift. Also makes the space feel much more comfortable to work in.
• 14-foot legs and above: Needed for tall RVs, commercial equipment, or if you plan to install a full two-post or four-post lift.

Do not underestimate how much leg height matters. A garage with 8-foot legs feels cramped fast. Go at least 10 feet, and if you have any doubt, go 12.

Plan for Future Use

The most common thing we hear from customers is: "I wish I had gone bigger." Metal buildings are a long-term investment. The cost difference between a 24×30 and a 30×40 is far less than the cost of adding on later — or replacing the building entirely.

Ask yourself:

• Will I ever add another vehicle?
• Do I plan to do more work in this space over time?
• Could this become a workshop, gym, or hobby space someday?
• Might I need to store a boat, RV, or trailer in the future?

If you answered yes to any of those, size up. It is almost always worth it.

Common Sizing Mistakes to Avoid

Ordering the minimum: The smallest building that technically fits your vehicles will feel cramped from day one. Always add at least 4–6 feet to your minimum calculation.

Forgetting the door swing: Walk-in doors swing inward. Make sure there is clearance behind the door so it does not hit a vehicle or a wall.

Not accounting for the roof pitch: On an A-frame or vertical roof, the peak is higher than the legs. But the usable interior height at the walls is determined by leg height — not the peak. Plan accordingly.

Ignoring the site: If your site has a slope, drainage issues, or limited access, those factors affect what size and orientation will work. Talk to your dealer before you order.

Skipping the concrete conversation: If you are pouring a concrete slab, the slab needs to be sized correctly for the building. Order the building first, then size the slab to match — not the other way around.

A Simple Sizing Formula

If you want a quick starting point, use this formula:

1. Add up the widths of all vehicles + 6 ft per vehicle for clearance = building width
2. Take the length of your longest vehicle + 8 ft for front/rear clearance = building length
3. Add 10 ft to the length if you want a work or storage area
4. Choose leg height based on your tallest vehicle + 2 ft minimum clearance

Then round up to the nearest standard size. Common sizes we sell most often for garages: 20×30, 24×30, 24×40, 30×40, 30×50, and 40×60.

Ready to Get a Quote?

Once you know your size, getting a quote is fast. At Rescue Metal Designs, we can walk you through every option — roof style, door placement, leg height, and color — and get you a price the same day.

Give us a call or fill out our contact form and we will help you size it right the first time.