How many bundles of shingles do I need for a 1,200 square foot house?

It depends on pitch and overhang. A 1,200 square foot footprint at 6/12 pitch is 1,200 × 1.118 = 1,341.6 square feet of roof, or 13.42 squares. At 3 bundles per square that is 41 bundles before waste, about 45 with 10% waste.

How many bundles are in a square of shingles?

Most three-tab and architectural shingles are packed 3 bundles per square (100 square feet). Some heavier designer shingles are 4 or 5 bundles per square, so check the coverage printed on the bundle.

How much waste should I add for shingles?

About 10% on a simple gable roof and 15% on hip roofs or roofs with valleys and dormers, because more shingles are cut at hips, valleys and rakes.

Roofing Calculator: Roof Area, Squares, Bundles

Materials

Roof area–

Squares–

Shingle bundles–

Underlayment–

Slope factor–

Drip edge–

Ridge cap–

Estimate only. Bundles per square and roll coverage vary by product: check the label. Order a little extra for starter strips, and confirm counts with your supplier.

Roofing materials

Roof shingles at Home Depot.
Drip edge in 10' lengths.
Pitch gauges for reading the roof from the ground or a ladder.

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How roof area is worked out

Measure the house on the ground, add the overhang on every side, and multiply that footprint by the slope factor √(1 + (pitch ÷ 12)²). For a single-pitch gable or hip roof the hips don't change the total: every plane has the same slope, so area = footprint × factor. A 1,200 sq ft footprint at 6/12 is 1,200 × 1.118 = 1,341.6 sq ft.

A square is 100 sq ft. Most shingles come 3 bundles per square (GAF explains it here); check yours. Add waste: about 10% for a gable, 15% for a hip or a roof with valleys and dormers.

Drip edge runs along eaves and rakes (gable) or all eaves (hip), sold in 10' pieces. Ridge cap covers ridges and hips; we assume 25 linear feet per bundle, but it varies widely by product.

By plane is for roofs with sections at different pitches or an L-shape: enter each plane's level length and run (eave to ridge, including overhang) and its pitch.

Questions

How many bundles of shingles for a 1,200 sq ft house?

At 6/12 pitch with the overhang included in the 1,200 sq ft, it's 1,341.6 sq ft of roof, 13.42 squares, 41 bundles before waste, about 45 with 10% waste.

How many bundles are in a square?

Usually 3. Some heavier designer shingles are 4 or 5 per square; the coverage is printed on the bundle.

How much waste should I add?

About 10% on a simple gable roof, 15% on hip roofs or roofs with valleys and dormers.

Don't know the pitch? Use the roof pitch calculator. Cutting rafters? Try the rafter length calculator.

Safety

Roof work is a fall risk. Use fall protection (OSHA guidance), or hire a licensed roofer. Re-roofing usually needs a permit; check local code for underlayment, ice barrier and layer limits.