Most asphalt shingles are packed three bundles to a “square”, and one square covers 100 sq ft of roof. So a roof with 2,000 sq ft of plan area (the footprint including the overhangs) at a common 6/12 pitch needs about 74 bundles once you add 10% for waste.
The catch is that the roof surface is always bigger than the footprint, because it slopes. Below is how to allow for that, a quick table, and the extras people forget to order.
Quick answer: bundles by roof size
These figures assume a 6/12 pitch, a simple gable roof, 10% waste and three bundles per square.
| Roof plan area (incl. overhangs) | Actual roof area | Squares (with waste) | Bundles |
|---|---|---|---|
| 1,000 sq ft | 1,118 sq ft | 12.3 | 37 |
| 1,500 sq ft | 1,677 sq ft | 18.4 | 56 |
| 2,000 sq ft | 2,236 sq ft | 24.6 | 74 |
| 2,500 sq ft | 2,795 sq ft | 30.7 | 93 |
For a hip roof, or a roof with valleys and dormers, use 15% waste instead of 10%. That adds three or four bundles on a 2,000 sq ft roof.
How to work it out
- Measure the plan area. Measure the length and width of the house and add the eave and gable overhangs. A 50 × 36 ft house with 1 ft overhangs all round is 52 × 38 = 1,976 sq ft of plan area.
- Find the pitch. Pitch is how many inches the roof rises for every 12 inches it runs. Put a level on the rafter or roof, measure 12 inches along it, then measure straight up to the roof. A 6 inch rise means 6/12.
- Multiply by the pitch factor from the table below to get the real sloped area.
- Add waste. Add 10% for a plain gable roof and 15% for hips, valleys and lots of cuts.
- Convert to squares and bundles. Divide by 100 for squares, then multiply by three for bundles. Always round up.
Pitch factors
| Pitch | Multiply plan area by |
|---|---|
| 4/12 | 1.054 |
| 5/12 | 1.083 |
| 6/12 | 1.118 |
| 7/12 | 1.158 |
| 8/12 | 1.202 |
| 9/12 | 1.250 |
| 10/12 | 1.302 |
| 12/12 | 1.414 |
Worked example. A 1,976 sq ft plan area at 8/12 pitch is 1,976 × 1.202 = 2,375 sq ft of roof. A hip roof needs 15% waste, which makes it 2,731 sq ft, or 27.3 squares. At three bundles per square that is 81.9, so order 82 bundles.
If you would rather skip the arithmetic, the DIYMeter roofing calculator does all five steps for you, in feet or metres.
Check the bundle label first
Three bundles per square is the norm for standard 3-tab and most architectural (laminated) shingles. Some heavier designer shingles come four or even five bundles to a square. The coverage is printed on every bundle, so check it before you order.
Don’t forget the extras
- Starter strip. You need this along every eave and rake edge. Measure those edges and buy starter shingles by the linear foot shown on the pack.
- Ridge and hip cap. Add up the length of all the ridges and hips. One bundle of cap shingles usually covers 20 to 35 linear feet, depending on the brand.
- Underlayment. Many synthetic underlayment rolls cover about 10 squares, and a roll of #15 felt covers roughly 4 squares. Check the label, because roll sizes vary.
- Drip edge. Comes in 10 ft lengths. Divide the total eave and rake length by 10 and round up.
- Nails. With four nails per shingle you need about 2 to 2.5 lb of roofing nails per square. In high-wind areas, where codes ask for six nails, allow about half as much again.
- Ice and water shield. Most building codes in cold regions of the US and Canada require it along the eaves, and it is wise in valleys anywhere.
Working in metres?
One square is 100 sq ft, which is about 9.29 m². To convert, divide your roof area in m² by 9.29 to get squares. A roof of 230 m² is about 24.8 squares before waste.
Asphalt shingles are common in the US, Canada and parts of Australia. In the UK most pitched roofs are tiled or slated, and those are counted per m² from the gauge and the tile size rather than in squares.
Common mistakes
- Using the floor area of the house. The roof is larger because of the overhangs and the slope. On a steep roof the difference can be 30% or more.
- Forgetting garages and porches. Measure every roof plane that is being re-roofed.
- Ordering exactly the number you calculated. Shingles come from dye lots, and a bundle bought later may not match in colour. One or two spare bundles are cheap insurance, and most suppliers will take back unopened bundles.
FAQs
How many square feet does a bundle of shingles cover? About 33.3 sq ft when there are three bundles to a square.
Can I walk on a 9/12 roof? Anything steeper than about 7/12 is hard to walk on safely. Use roof jacks and a harness, or leave it to a roofer.
Related: the DIY Project Budget & Materials Planner turns your measurements into quantities, costs and a shopping list.
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