Shingle Size Chart: Bundles, Squares & Roof Coverage Guide

How a roof is sized in shingles

A roof is sized in bundles, and a bundle is sized in square feet. One bundle of shingles covers 33.33 sq ft, and 3 bundles make one roofing square, which is 100 sq ft. The material needed is the roof area plus the waste factor — the extra for cuts, valleys, hips and the starter course, 10% by default. The squares are the material divided by 100. The bundles are the material divided by 33.33, rounded UP — a partial bundle is still a bundle, so the count always rounds up, never down. The cost is the bundles times the price per bundle. Sizes are typical manufacturer sizes and vary by brand, so check the bundle label before you buy.

At the defaults — a 1,800 sq ft roof, 10% waste, $35.00 a bundle — the material needed is 1,800 × 1.10 = 1,980.00 sq ft. The squares are 1,980.00 ÷ 100 = 19.80 squares. The bundles are 1,980.00 ÷ 33.33 = 59.41, rounded up to 60 bundles. The cost is 60 × $35.00 = $2,100.00.

The worked example, line by line

Setup: roof area 1,800 sq ft, waste 10%, price $35.00 a bundle.

Line 1 — the material needed. 1,800 × 1.10 = 1,980.00 sq ft.

Line 2 — the squares. 1,980.00 ÷ 100 = 19.80 squares.

Line 3 — the bundles. 1,980.00 ÷ 33.33 = 59.41, rounded up to 60 bundles.

Line 4 — the cost. 60 × $35.00 = $2,100.00.

Reverse: 50 bundles at 10% waste cover a 1,515.00 sq ft roof; a 2,000 sq ft roof at 10% waste needs 67 bundles; 60 bundles at $40.00 a bundle are $2,400.00; 100 bundles at 10% waste cover 3,030.00 sq ft; 11.10% waste makes 60 bundles exactly cover an 1,800 sq ft roof (60 × 33.33 = 1,999.80 sq ft; (1,999.80 − 1,800) ÷ 1,800 = 11.10%).

Every branch, checked

Roof 1,200 sq ft: the material is 1,200 × 1.10 = 1,320.00 sq ft, which is 13.20 squares and 1,320.00 ÷ 33.33 = 39.60, rounded up to 40 bundles. Cost $1,400.00.

Roof 2,400 sq ft: the material is 2,640.00 sq ft, 26.40 squares, 80 bundles, cost $2,800.00.

Roof 3,000 sq ft: the material is 3,300.00 sq ft, 33.00 squares, and 3,300.00 ÷ 33.33 = 99.01, which rounds up to 100 bundles. Cost $3,500.00. One hundredth of a bundle over the line is a whole extra bundle — that is the round-up rule doing its job.

Roof 900 sq ft: the material is 990.00 sq ft, 9.90 squares, 30 bundles, cost $1,050.00.

Roof 2,000 sq ft: the material is 2,200.00 sq ft, 22.00 squares, and 2,200.00 ÷ 33.33 = 66.01, which rounds up to 67 bundles. Cost $2,345.00.

Waste 15%: the material is 1,800 × 1.15 = 2,070.00 sq ft, 20.70 squares, 63 bundles, cost $2,205.00. Five more points of waste are worth 3 bundles and $105.00.

Waste 5%: the material is 1,890.00 sq ft, 18.90 squares, 57 bundles, cost $1,995.00.

Waste 0%: the material is 1,800.00 sq ft, 18.00 squares, and 1,800.00 ÷ 33.33 = 54.01, which rounds up to 55 bundles. Cost $1,925.00. Zero waste still needs the extra bundle — the roof is 54.01 bundles, not 54, and you cannot buy one hundredth of a bundle.

Price $45.00/bundle: the count stays 60 bundles, but the cost is 60 × $45.00 = $2,700.00.

Price $28.00/bundle: 60 bundles, cost $1,680.00.

Reverse — the other way round: 50 bundles at 10% waste cover a 1,515.00 sq ft roof; a 2,000 sq ft roof at 10% waste needs 67 bundles; 60 bundles at $40.00 a bundle are $2,400.00; 100 bundles at 10% waste cover 3,030.00 sq ft; 11.10% waste makes 60 bundles exactly cover an 1,800 sq ft roof.

What the defaults assume

The model assumes the roof area, waste factor and price per bundle you enter, one bundle covering 33.33 sq ft, and the table’s typical manufacturer sizes. It assumes the roof area you enter is the area to be shingled, not the footprint of the house — a pitched roof has more area than the floor below it, so measure the roof, not the plan. It leaves out underlayment, flashing, ridge caps, drip edge and labour, and it assumes the waste factor you pick covers the cuts — a cut-up roof with lots of valleys needs more than 10%. Rounding convention: material and squares are shown to two decimals, the bundle count is a whole number rounded up, money is rounded to cents, and all figures are computed from unrounded values, rounded only for display.

Output · formula · meaning

Who uses this

• The homeowner pricing a new roof: they learn an 1,800 sq ft roof needs 60 bundles and $2,100.00 of shingles — so they know the shopping list, and they check the $45.00-a-bundle case at $2,700.00 before choosing the shingle.
• The roofer working out a quote: they learn 50 bundles cover a 1,515.00 sq ft roof at 10% waste — so they know how far the stock on the truck goes, and they check the 100-bundle case at 3,030.00 sq ft before ordering.
• The DIYer with a cut-up roof: they learn 15% waste needs 63 bundles where 10% needs 60 — so they know the valleys cost 3 bundles, and they check the 0%-waste case at 55 bundles before deciding the allowance is too generous.
• The budget builder stretching the money: they learn 60 bundles at $40.00 a bundle are $2,400.00 — so they know the cost of the better shingle, and they check the $28.00-a-bundle case at $1,680.00 before choosing the grade.

Accuracy & limitations

The math is exact for the numbers you enter: the material is the roof area times one plus the waste, the bundles are the material divided by 33.33 rounded up, and the cost is the bundles times the price. What the model cannot do is measure your roof: check the area, because a pitched roof has more area than the floor below it, and a roof measured from the plan will come up short. It assumes the bundle covers 33.33 sq ft and leaves out underlayment, flashing, ridge caps, drip edge and labour. Sizes are typical manufacturer sizes and vary by brand — check the bundle label. For the cost of the whole roof job, see concrete driveway cost calculator for the same kind of sizing on a driveway; for the lumber behind a deck, see board foot calculator.