Garage Siding Calculator
Siding a garage? Get squares, material and cost with the big garage-door opening properly subtracted.
Walls (feet)
Gables / triangles optional
Windows & doors to subtract
Tip: measure each wall's width × height at its widest points. A per-wall audit table appears below so you can check every number.
Your siding squares, panels and cost appear here.
Estimated from wall count and perimeter — confirm against your actual corners and openings.
Cost per sq ft: – · per square: –
| Surface | Area (sq ft) |
|---|
Garages: one big opening, one gable
A garage is a simple structure with two quirks that matter for siding: a large garage-door opening that removes a real chunk of wall, and usually a gable end you shouldn't overlook. Get those two right and the rest is four straightforward walls. This calculator lets you enter the garage door as an opening and the gable as a triangle, so the deduction and the addition both land correctly.
It works for detached garages, attached ones, and outbuildings alike. Enter the walls, drop in the door sizes, add the gable, and read your squares and cost.
A quick walk-through
Think of it as describing your house to the tool. First tell it what you're installing and in which units — that's the material dropdown and the feet/meters toggle. Then describe the walls: one row each for the front, back and sides, with the width, height and how many are the same.
Now the details that trip most people up. Any triangular gable goes in with its base and its height to the peak. Every window and door goes in as a size and a count so it's subtracted rather than covered. Last, choose how much waste to carry — 10% is the everyday figure — and, if you'd like a budget, add your labor and removal rates. Calculate, and read squares, panels, boxes, trim and cost in one place.
A two-car garage
Walls: two at 22 × 9 and two at 24 × 9 = 396 + 432 = 828 sq ft. Gable ½ × 24 × 6 = 72. Garage door 16 × 7 = 112, plus an entry door 3 × 7 = 21. Net = 828 + 72 − 133 = 767 sq ft ≈ 7.7 squares.
Data sources and limitations
Two kinds of numbers feed this tool. The geometry — areas, openings, squares, waste — is fixed arithmetic and as accurate as your tape. The material coverage and the cost estimates are planning values based on common manufacturer specifications and reported US installed pricing; they vary with product line, region and labor, which is why they appear as ranges. Treat the result as a solid starting point for budgeting and ordering, subject to a field measure and your contractor's quote.
Details that make or break the order
You've got a number — now protect it. These are the checks that keep a garage siding order from coming up short or over-buying.
- Confirm coverage: the default coverage is a planning figure. Check the exact coverage printed on your product's box or spec sheet and adjust it if it differs, since even a small change moves the piece count on a big wall.
- Match the waste to your walls: keep 10% for a simple rectangular house, and raise it toward 15% for gables, dormers, bay windows and lots of angled cuts, because those details generate short offcuts you can't reuse.
- Account for accessories: starter strip, trim, inside and outside corners, flashing and fasteners are all part of a complete order, not an afterthought — the takeoff above estimates each so your material list is whole.
- Keep a spare: hold back a piece or a full box for future repairs, since profiles and colors get discontinued over time and an exact match years later is hard to find.
- Time your order: have material delivered close to the start date, stored flat and dry, so it isn't sitting exposed or getting damaged before the crew arrives.
Re-run the numbers above after any change and lean on the per-wall audit to verify each surface one at a time, so what you order matches what the wall actually needs rather than a rough guess. That small habit is the difference between one clean delivery and a mid-project trip back to the supplier.
Frequently asked questions
How much siding does a garage need?
Do I subtract the garage door?
Should I match the garage to the house siding?
Does a garage have a gable?
What homeowners say
"Subtracting the big door made the difference between one box too many and just right."