Work out how many roofing squares, bundles and shingles you need from your roof footprint and pitch — in metres or feet, with a wastage allowance for cuts, ridges and starter courses.
Enter your roof footprint and pitch below — the calculator converts it to roofing squares (the standard unit used in both Australia and the US), then tells you how many bundles and the estimated cost.
| Item | Value |
|---|
Asphalt and composite shingles are measured in "squares" — one square covers 100 square feet (about 9.29 m²) of roof. Shingles are sold in bundles, and it usually takes three bundles to cover one square, though heavier architectural shingles may need four.
| Shingle type | Bundles per square | Notes |
|---|---|---|
| Standard 3-tab asphalt | 3 | Most common, lightest |
| Architectural / laminate | 3–4 | Heavier, longer lasting |
| Premium / designer | 4–5 | Thickest profile |
A house with a 12 m × 8 m footprint and a medium pitch has a plan area of 96 m². Applying the medium-pitch factor of 1.082 (22.5°) gives an actual roof area of about 103.9 m². Adding 12% wastage brings it to roughly 116.4 m². Dividing by 9.29 (the size of one roofing "square") gives about 12.5 squares, and at 3 bundles per square that’s 38 bundles of shingles.
Getting a shingle order right is about more than the roof area. Start by measuring the footprint accurately and choosing the correct pitch, because the slope multiplier has a real effect — a steep 12:12 roof has over 40% more surface area than its footprint, while a low 4:12 roof adds only about 5%. Underestimate the pitch and you’ll come up short. On top of the field shingles, remember that hips, ridges and starter courses all consume extra material, which is why a 10–15% wastage allowance is standard rather than optional.
It’s also worth ordering all your shingles in one go from the same production batch. Asphalt shingle colour can vary slightly between batches, and a repair or top-up bought months later may not match the original roof. Keeping a few spare bundles from the original order means you have matching stock on hand for storm damage or repairs down the track. Finally, if your roof has multiple sections or dormers, calculate each roof plane separately and add them together, rather than treating the whole thing as one rectangle — complex roofs generate more offcuts and need a slightly higher wastage margin.
| Tip | Why it matters |
|---|---|
| Measure the plan footprint, not the slope | The calculator applies the pitch factor for you |
| Add 10–15% wastage | Covers cuts at hips, valleys, ridges and starter rows |
| Buy from one batch | Colour can vary slightly between production runs |
| Keep a few spare bundles | Storm repairs are easier with matching shingles on hand |
A "square" is the standard roofing measurement in both the US and Australia: 1 square = 100 sq ft = 9.2903 m². This calculator works entirely in squares, so the results are the same whether you enter your footprint in feet or metres — just use the toggle above to match how you measure.
| Shingle style | Typical use | Bundles per square |
|---|---|---|
| Standard 3-tab asphalt | Budget re-roofs, rentals | 3 |
| Architectural / dimensional shingles | Most common on new US homes | 3-4 |
| Premium / designer shingles | High-end, longer warranty | 4-5 |
How many bundles of shingles do I need?
It usually takes three bundles of standard asphalt shingles to cover one roofing "square" (100 sq ft / 9.29 m²). Architectural shingles often need 3-4 bundles per square. Work out your roof area in squares, then multiply by the bundles-per-square for your product — this calculator does it for you, in metres or feet.
How do I measure my roof area for shingles?
Measure the length and width of the building footprint (in feet or metres), then account for the roof slope using the pitch. A steeper roof has more actual surface area than its footprint suggests, so the calculator multiplies by a pitch factor to give the true area to shingle.
How many bundles of shingles are in a square?
Most standard 3-tab asphalt shingles come three bundles to a square. Heavier architectural or dimensional shingles typically need 3-4 bundles per square, and premium/designer shingles can need 4-5, so always check the coverage stated on your product's packaging.
How much does a new roof cost?
Roofing cost depends heavily on total squares, pitch, shingle type and labour rates in your area. As a starting point, multiply your roofing squares by the bundles needed per square and your local cost per bundle — this calculator gives you that material estimate, though a full roof quote should also include labour, underlayment, flashing and disposal.
How much extra should I order for wastage?
Allow 10-15% extra for cuts around hips, valleys, ridges, and starter courses — more on a complex roof with many angles. The calculator defaults to 12%. It's also worth keeping a few spare shingles from the same batch for future storm repairs.
How do I measure a roof I can't safely climb?
Estimate roof area from the ground by measuring the building footprint (length × width of the outer walls) and applying the pitch multiplier — exactly how this calculator works. For an exact figure on a complex roof, a roofer can measure it directly or use satellite measurement tools.
Should I order extra shingles for repairs?
Yes. Order a little extra beyond the calculated amount and keep the spare bundles. Shingle colour varies between production batches, so matching stock bought later may not blend with the existing roof.