Turn roof area or footprint and pitch into squares, bundles, underlayment, ridge cap and nails.
Quick answer: Roofing is sold by the square, which is 100 sq ft of finished roof. A 1,342 sq ft roof plus 10 percent waste is about 1,476 sq ft, or 14.8 squares. At the typical three bundles per square that is 45 bundles, plus underlayment, ridge cap and roughly 2.5 lb of nails per square.
How do you know the roof size?
sq ft
The floor area the roof covers; the slope adds surface on top.
in
Multiplier at this pitch: 1.118
%
10% suits a simple gable; hips, valleys and dormers need 15%.
Usually 3 for standard shingles, 4+ for heavier architectural.
$
Standard asphalt shingle material runs roughly $90–$200 per square; architectural grades sit at the top of that range.
Shingle bundles
56
18.45 squares (1,845 sq ft with waste)
Material estimate
$2,583
2 rolls of underlayment
Full roofing list
Roof surface1,677 sq ft
With 10% waste1,845 sq ft = 18.45 squares
Shingle bundles56
Underlayment rolls2
Ridge and hip cap1 bundles (about 30 linear ft per bundle)
Roofing nailsabout 46 lb (roughly 2.5 lb per square)
Starter striplinear feet of eaves, plus rake edges if your product needs it
Material estimate$2,583
Tear-off, underlayment, flashing, drip edge and labour are usually quoted separately from the shingle material. A full replacement typically prices the whole assembly per square rather than per bundle.
Three bundles per square is the usual figure for standard asphalt shingles, but heavyweight architectural products often need four or more. Always order from the bundle count on the wrapper, and keep one spare bundle for repairs.
Core facts
One square
100 sq ft of roof surface
Bundles
Typically 3 per square
Underlayment
About 1,000 sq ft per roll
Nails
Roughly 2.5 lb per square
What is Shingle Calculator?
Asphalt shingles are sold by the square, and a square is 100 sq ft of finished roof surface. If you know the roof area, divide by 100. If you only know the footprint, multiply it by the pitch multiplier first — a 6/12 roof adds about 12 percent to the footprint area. Then add waste: 10 percent covers most simple gable roofs, and 15 percent is safer on a roof with hips, valleys and dormers where a lot of material gets cut. The calculator turns the total into bundles at three per square by default, plus underlayment, ridge cap and nails, and every default can be changed to match the product you are buying.
Common uses for Shingle Calculator
Order shingles for a simple gable roof from the footprint area
Check a roofing quote by counting squares and bundles yourself
Add waste for a roof with valleys, hips and dormers
Work out underlayment rolls and nails for the same order
Compare the coverage per bundle of three-tab and architectural shingles
Squares, bundles and what a roofer means by a square
One square is 100 sq ft of roof. A shingle bundle usually covers a third of a square, so three bundles make a square on most products. Steep roofs, heavy laminate shingles and lots of cutting all push real coverage down, which is why the waste percentage matters more on a complex roof than on a plain one. Always round up to whole bundles.
The extras that turn up on every roofing order
Underlayment, drip edge, ridge cap, starter strip, valley flashing, pipe boots and nails are separate line items, and they are easy to forget when you are focused on shingles. Starter strip runs the length of the eaves and rakes; ridge cap covers ridges and hips. The calculator estimates ridge cap from roof area as a rough allowance, so measure your actual ridge and hip runs and use the coverage printed on the cap bundle.
Measuring a roof without climbing it
You can get a usable area from the ground: measure the footprint of the house, add the overhang, then multiply by the pitch multiplier. Add area for a garage, porch or dormer that shares the roof, and allow a little extra for the surface a hip or valley creates. On a roof you can walk, measure each plane and add them up. Either way, get the pitch before you order.
Frequently Asked Questions
How many bundles of shingles are in a square?
Most asphalt shingles are packaged at three bundles per square, which is 100 sq ft of coverage. Heavier architectural products may need four bundles per square or state their own coverage. The calculator defaults to three and lets you change it, so check the bundle label before you order.
How much waste should I add for shingles?
Ten percent is the usual starting figure for a simple gable roof. Increase it to 15 percent for hips, valleys, dormers or a steep pitch, where more cutting is needed. Keep a spare bundle or two for repairs, because shingle colors shift slightly between production runs.
Do I need underlayment over the whole roof?
Yes on a typical shingle roof. The calculator assumes one roll per 1,000 sq ft, which suits many synthetic underlayments, while traditional felt rolls often cover about 400 sq ft. Ice and water membrane is additional and usually runs along the eaves and in valleys. Check the manufacturer's requirements for your slope.
How many nails do I need?
Hand-nailing typically uses a few pounds of nails per square, and the calculator estimates about 2.5 lb as a rule of thumb. Coil nails for a pneumatic gun are counted in coils, and heavy textured shingles need more. Follow the manufacturer's nailing schedule, because that is what the warranty references.
Can I enter the footprint instead of the roof area?
Yes, if you also give the pitch. A roof has more surface than the floor beneath it: a 6/12 roof adds about 12 percent and a 12/12 roof about 41 percent. Enter the footprint and the pitch and the calculator applies the multiplier for you, or enter a measured roof area directly.