Free tool · Takeoff
Roofing Squares Calculator
Roofing is sold by the square, which is 100 square feet of roof. Enter the outline of each roof section as seen from above, with its pitch, and the calculator turns it into roof surface, squares, bundles of shingles and rolls of underlayment. If you already know a section’s surface area, you can enter that instead.
The numbers stay in your browser: we do not store or receive them.
Roof sections
For each section enter the outline of the roof seen from above and its pitch, or a surface area you already know. Leave a row blank to skip it.
Ordering
Roof area
15.03 squares
1,503 sq ft
With 10.0% waste
16.53 squares
Bundles to order
50
16.67 squares at 3 per square
Underlayment rolls
4
| Section | Plan area (sq ft) | Slope factor | Pitch angle | Surface (sq ft) | Squares |
|---|---|---|---|---|---|
| Section 1 | 1,344 | 1.1180 | 26.6° | 1,503 | 15.03 |
Why pitch matters
A sloped roof has more surface than the floor plan beneath it. The pitch is the rise in inches for every 12 inches of run, so a 6/12 roof rises 6 inches per foot. The slope factor is the diagonal of that triangle: √(1 + (rise ÷ 12)²). Multiply the plan area by the slope factor to get the roof surface.
Common factors are 1.054 at 4/12, 1.118 at 6/12, 1.202 at 8/12 and 1.414 at 12/12. Any roof shape with a single pitch, whether gable, hip or shed, has the same surface as its outline multiplied by the factor, so the outline is all you need.
Overhang, waste and bundles
Overhang adds to each side of the outline you enter. Use the building size and let the overhang box add the eaves and rakes, or enter the full roof outline and set the overhang to zero.
Waste covers cuts, hips, valleys and rejects. A plain gable is often figured at about 10 percent and a cut-up roof with many hips and valleys at 15 percent or more. The box is yours to change.
Bundles per square is printed on the shingle package. Many asphalt shingles come three bundles to the square and some heavier types four. The order is rounded up to a whole bundle.
A worked example
A 40 ft by 30 ft house with a 1 ft overhang all around has an outline of 42 ft by 32 ft, or 1,344 sq ft. At 6/12 the slope factor is 1.118, so the roof is 1,503 sq ft, or 15.03 squares.
With 10 percent waste that is 16.53 squares. At three bundles per square it takes 49.6, so 50 bundles. Underlayment rolls that cover 400 sq ft each take 4 rolls.
What this does not do
It does not add starter strips, ridge and hip caps, drip edge, flashing, nails, or ice and water shield, and it does not subtract skylights or chimneys. A roof with different pitches needs a section for each pitch. The underlayment count uses the roof surface without waste because the roll coverage on the package already allows for laps. Check the coverage and bundle counts on the products you buy.
FAQ
How many square feet is a roofing square?
One roofing square is 100 square feet of roof surface. A 1,500 sq ft roof is 15 squares.
How many bundles of shingles are in a square?
Many asphalt shingles are three bundles to a square and some heavier laminated types are four. The package says, so enter that number.
How do I find the pitch of a roof?
Hold a level 12 inches out from the roof and measure straight down to the roof surface. That distance in inches is the rise per 12, so 6 inches is a 6/12 pitch. Plans usually show it as a small triangle with the numbers.
Do I use the building size or the roof size?
Use the outline as seen from above. If you use the building size, the overhang box adds the eaves and rakes. If you already measured the full roof outline, set the overhang to zero.
How much waste should I add?
About 10 percent is common for a simple gable and 15 percent or more for a roof with many hips, valleys and dormers. Your layout and the shingle type change it.
Is anything I type saved?
No. The calculation runs in your browser and nothing is stored or sent to us.
Pricing the whole roof? PoPs Estimating measures areas from your plans and keeps the quantities tied to the bid.
Questions?
Ask us anything about PoPs Suite, pricing, or running a construction company. A real person answers, usually within a business day.