Measure from the ground, not the roof
You don't need to climb up. Measure the outside walls, then add the overhang (eaves and rakes) on each side. The overhang is often 12–24 in, and you can measure it from the ground or from a ladder at the eave. Then:
- Split the roof into sections, rectangles in plan view: the main house, a garage wing, a porch roof. Enter the first section, then add the others with “+ Another section”.
- Give each section its pitch and shape: gable (two slopes and a ridge along the length), hip (slopes on all four sides) or shed (one slope). A porch roof at a lower pitch is simply another section.
- Find each pitch with the roof pitch calculator: measure the rise over 12 in of run from the attic or on a gable end.
From footprint to bundles
- Pitch multiplier = √(1 + (rise ÷ 12)²). For a 6/12 roof that's 1.118.
- Section area = footprint × its multiplier. The sections are added up, so a 40 × 30 ft footprint at 6/12 gives 1,341.6 ft².
- Squares = roof area × (1 + waste) ÷ 100. One roofing square is 100 ft².
- Bundles = squares × bundles per square, rounded up.
With 10% waste and 3 bundles per square, that example needs 45 bundles.
Eaves, rakes, hips, ridges and valleys
The edge lengths drive everything except the shingles. The calculator estimates them from each section's shape. Where you know the real lengths, enter them under “Measured edges”, because measured totals replace the estimates.
| Section shape | Eaves | Rakes (sloped) | Ridge | Hips |
|---|---|---|---|---|
| Gable | 2 × length | 2 × width × pitch multiplier | length | none |
| Hip | perimeter: 2 × (length + width) | none | length − width | 4 × (width ÷ 2) × √(2 + (rise ÷ 12)²) |
| Shed | length (low edge) | 2 × width × pitch multiplier | none (high edge needs its own trim) | none |
Valleys form where sections meet. Their length depends on how the roofs intersect, so measure them and enter the total. When sections join, some estimated eaves and rakes end up hidden against the other roof, so measured edges give a tighter order.
Starter strip, ridge cap, nails and valleys
- Starter strip runs along the eaves and, with many products, the rakes too. Owens Corning's Starter Strip Plus is applied at both, and one bundle covers 105 lineal ft. Bundles = starter length ÷ coverage per bundle. You can switch to eaves only.
- Hip and ridge cap: add every hip and ridge and divide by the bundle coverage. Owens Corning ProEdge lists 33 ft per bundle. Other brands' bundles cover different lengths, so change the coverage under “Product sizes, prices and costs”.
- Nails = squares × shingles per square × nails per shingle. Owens Corning's Duration data gives 64 shingles per square and a 4-nail pattern, which is 256 nails per square. Use 6 where the manufacturer's instructions or local code require the high-wind pattern.
- Valley lining: the IRC (R905.2.8.2) requires valley linings, for example at least 36 in wide for closed valleys. The calculator lists your measured valley length so you can buy the lining by the roll.
| Roof (gable, 10% waste) | Starter strip | Ridge cap | Nails |
|---|---|---|---|
| 30 × 24 ft at 4/12 | 2 | 1 | 2,138 |
| 40 × 30 ft at 6/12 | 2 | 2 | 3,779 |
| 50 × 30 ft at 8/12 | 2 | 2 | 5,077 |
| Roof (gable, 10% waste) | Starter strip | Ridge cap | Nails |
|---|---|---|---|
| 9 × 7.2 m at 20° | 2 | 1 | 2,091 |
| 12 × 9 m at 25° | 2 | 2 | 3,613 |
| 15 × 9 m at 30° | 2 | 2 | 4,726 |
Bundles per square: check the wrapper
Most standard three-tab and laminated (architectural) shingles come 3 bundles per square. Read the wrapper, though. Owens Corning's TruDefinition Duration data, for example, lists 3 bundles per square but a coverage of 98.4 ft² per square, not a full 100. Heavier designer shingles can be 4 or more bundles per square. If your shingle covers slightly less than 100 ft² per square, raise the waste a point or two, or divide the roof area by the stated coverage.
Waste factor by roof type
Waste covers cutting at rakes, hips and valleys, and damaged pieces. As a rough guide, simple gable roofs often use about 10%, and hip roofs or roofs with valleys and dormers 15% or more (approximate). Starter and ridge cap are counted separately above.
| Footprint (incl. overhang) | Pitch | Roof area | Bundles at 10% | Bundles at 15% |
|---|---|---|---|---|
| 30 × 24 ft | 4/12 | 758.9 ft² | 26 | 27 |
| 40 × 30 ft | 6/12 | 1,341.6 ft² | 45 | 47 |
| 50 × 30 ft | 8/12 | 1,802.8 ft² | 60 | 63 |
| 60 × 32 ft | 6/12 | 2,146.6 ft² | 71 | 75 |
| 40 × 30 ft | 10/12 | 1,562 ft² | 52 | 54 |
| Footprint (incl. overhang) | Pitch | Roof area | Bundles at 10% | Bundles at 15% |
|---|---|---|---|---|
| 9 × 7.2 m | 20° | 69 m² | 25 | 26 |
| 12 × 9 m | 25° | 119.2 m² | 43 | 45 |
| 15 × 9 m | 30° | 155.9 m² | 56 | 58 |
| 18 × 9.6 m | 25° | 190.7 m² | 68 | 71 |
| 12 × 9 m | 40° | 141 m² | 51 | 53 |
Underlayment, drip edge and the rest
- Underlayment: rolls list their coverage. Synthetic rolls often cover far more than felt. Enter the roll coverage, and the calculator divides the roof area (with waste) by it. On slopes from 2:12 up to 4:12, the IRC (R905.2.2) and ARMA call for double underlayment or a self-adhering membrane, and asphalt shingles aren't installed below 2:12. The calculator flags any section in those ranges.
- Ice barrier: in areas with a history of ice damming, code requires an ice barrier at the eaves. Your local building department knows whether that applies to you.
- Drip edge = eaves + rakes, from the estimates above or your measured edges.
- Vents, pipe boots and step or wall flashing depend on the house. Count them on site.
Worked examples
Ranch house, 48 × 28 ft footprint, 4/12 gableRanch house, 14.6 × 8.53 m footprint, 4/12 gable
Section length 48 ft · Section width 28 ft · Roof pitch 4/12 · Bundles per square 3 per square · Waste / overage 10 % · Underlayment roll coverage 1,000 ft²Section length 14.63 m · Section width 8.53 m · Roof pitch 18.4° · Coverage per bundle 3.1 m² · Waste / overage 10 % · Underlayment roll coverage 92.9 m²
- Bundles of shingles: 47
- Roof surface area: 1,416.7 ft²Roof surface area: 131.6 m²
- Squares (with waste): 15.58 squaresRoof area with waste: 144.8 m²
- Starter strip bundles (105 ft each): 2Starter strip bundles (32 m each): 2
- Hip & ridge cap bundles (33 ft each): 2Hip & ridge cap bundles (10.1 m each): 2
- Underlayment rolls: 2
- Drip edge (eaves + rakes): 155 ftDrip edge (eaves + rakes): 47.3 m
- Roofing nails (4 per shingle): 3,990
Two-story hip roof, 36 × 30 ft footprint, 8/12Two-story hip roof, 11 × 9.14 m footprint, 8/12
Section length 36 ft · Section width 30 ft · Roof pitch 8/12 · Section shape Hip (4 slopes) · Bundles per square 3 per square · Waste / overage 15 % · Underlayment roll coverage 1,000 ft²Section length 10.97 m · Section width 9.14 m · Roof pitch 33.7° · Section shape Hip (4 slopes) · Coverage per bundle 3.1 m² · Waste / overage 15 % · Underlayment roll coverage 92.9 m²
- Bundles of shingles: 45
- Roof surface area: 1,298 ft²Roof surface area: 120.6 m²
- Hips (estimated): 93.8 ftHips (estimated): 28.6 m
- Ridges (estimated): 6 ftRidges (estimated): 1.8 m
- Hip & ridge cap bundles (33 ft each): 4Hip & ridge cap bundles (10.1 m each): 4
- Drip edge (eaves + rakes): 132 ftDrip edge (eaves + rakes): 40.2 m
House with an attached garage: 40 × 28 ft at 6/12 gable plus a 24 × 22 ft hip at 4/12, 20 ft of valleysHouse with an attached garage: 12.2 × 8.5 m gable at 26.6° plus a 7.3 × 6.7 m hip at 18.4°, 6.1 m of valleys
Section length 40 ft · Section width 28 ft · Roof pitch 6/12 · Bundles per square 3 per square · Waste / overage 15 % · Valleys, measured 20 ft · Underlayment roll coverage 1,000 ft²Section length 12.19 m · Section width 8.53 m · Roof pitch 26.6° · Coverage per bundle 3.1 m² · Waste / overage 15 % · Valleys, measured 6.1 m · Underlayment roll coverage 92.9 m²
- Bundles of shingles: 63
- Roof surface area: 1,808.8 ft²Roof surface area: 168 m²
- Pitch multiplier (average): 1.098 ×
- Starter strip bundles (105 ft each): 3Starter strip bundles (32 m each): 3
- Hip & ridge cap bundles (33 ft each): 4Hip & ridge cap bundles (10.1 m each): 4
- Valley lining: 20 ftValley lining: 6.1 m
Shed-roof garage, 24 × 12 ft footprint, 3/12Shed-roof garage, 7.32 × 3.66 m footprint, 3/12
Section length 24 ft · Section width 12 ft · Roof pitch 3/12 · Section shape Shed (1 slope) · Bundles per square 3 per square · Waste / overage 10 % · Underlayment roll coverage 1,000 ft²Section length 7.32 m · Section width 3.66 m · Roof pitch 14° · Section shape Shed (1 slope) · Coverage per bundle 3.1 m² · Waste / overage 10 % · Underlayment roll coverage 92.9 m²
- Bundles of shingles: 10
- Roof surface area: 296.9 ft²Roof surface area: 27.6 m²
- Starter strip bundles (105 ft each): 1Starter strip bundles (32 m each): 1
- Drip edge (eaves + rakes): 48.7 ftDrip edge (eaves + rakes): 14.9 m
Below 4/12, double underlayment is required, so buy about twice the rolls shown.
Tear-off and layers
If you're replacing a roof, the number of existing layers matters for disposal and for code. Many jurisdictions limit how many layers of shingles you can have, and the IRC restricts re-covering in several situations. Dumpster size depends on squares and layers, so ask the hauler with your square count from this calculator. A roofer's estimate will also include deck repairs, which you can only see once the old roof is off.
Safety
OSHA identifies falls as the leading cause of death in construction. Measuring from the ground, as described above, avoids climbing for an estimate. If you do go up, use proper fall protection, a secured ladder that extends at least 3 ft above the landing (an OSHA ladder rule), and soft-soled shoes, and never work on a wet or frosty roof. Steep roofs are a job for professionals.
Checked against
Each case below is re-run against the calculator by our automated test suite.
| Case | Our result | Checked against | Result |
|---|---|---|---|
| 40 × 30 ft footprint at 6/12: roof surface | 1,341.6 ft² | Hand calculation | Match |
| Same roof as a hip roof: total hip length (4 hips) | 90 ft | Hand calculation | Match |
| Same gable roof: starter strip for eaves + rakes (147.1 ft) at 105 ft per bundle | 2 | Owens Corning Starter Strip Plus data sheet (105 lineal ft per bundle) | Match |
| Same gable roof: ridge cap for a 40 ft ridge at 33 ft per bundle | 2 | Owens Corning ProEdge Hip & Ridge spec sheet (33 ft per bundle) | Match |
| One square, no waste, 64 shingles per square, 4 nails each: nails | 256 | Owens Corning Duration product data (bundles and coverage) | Match |
| One square (100 ft²) of roof, no waste: bundles | 3 | Owens Corning Duration product data (bundles and coverage) | Match |
| Case | Our result | Checked against | Result |
|---|---|---|---|
| 12.2 × 9.14 m footprint at 6/12: roof surface | 124.6 m² | Hand calculation | Match |
| Same roof as a hip roof: total hip length (4 hips) | 27.4 m | Hand calculation | Match |
| One square (9.29 m²) of roof, no waste: bundles | 3 | Owens Corning Duration product data (bundles and coverage) | Match |
Frequently asked questions
How many bundles of shingles in a square?
Usually 3, but some heavy architectural shingles are 4. Check the wrapper.
How many bundles of shingles for 1,000 square feet?
10 squares × 3 = 30 bundles before waste, or 33 with 10%.
How many bundles for a 2,000 square foot roof?
60 bundles before waste, 66 with 10%. Note that 2,000 ft² of house is not 2,000 ft² of roof: multiply the footprint by the pitch multiplier first.
How do I handle a roof with different pitches?
Enter each part as its own section with its own pitch and shape. The calculator adds the sloped areas and the edges.
How many bundles of ridge cap do I need?
Add up all hips and ridges and divide by the bundle coverage, for example 33 ft for Owens Corning ProEdge. A 40 ft ridge needs 2 bundles.
How many nails per square of shingles?
About 256 for 64 shingles at 4 nails each, or 384 with a 6-nail pattern.
How do I measure a roof without climbing on it?
Measure the footprint including overhangs from the ground, find the pitch from the attic or a gable end, and multiply by the pitch multiplier.
Sources & assumptions
The results are planning estimates, and the cost figures only use prices you enter. Product yields, densities and coverage rates vary, so check the label or ask your supplier, and follow local codes. Figures marked "approximate" or "rule of thumb" are general practice, not exact standards.
- Owens Corning TruDefinition Duration shingles product data (bundles and coverage per square)
- Owens Corning Starter Strip Plus data sheet (105 lineal ft per bundle)
- Owens Corning ProEdge Hip & Ridge shingles specification sheet (33 ft per bundle)
- GAF Timberline HDZ shingles spec sheet (3 bundles and 64 pieces per square)
- GAF Pro-Start starter strip sell sheet (120.33 lf per bundle)
- GAF Seal-A-Ridge ridge cap sell sheet (25 lf per bundle)
- ARMA technical bulletin: Installation of Asphalt Shingles on Lower Sloped Roofs
- International Residential Code Chapter 9, Section R905.2 (asphalt shingles)
- OSHA: Fall Protection in Construction
- OSHA 29 CFR 1926.1053 (ladders)
See how we calculate and test our formulas and the changelog. Last updated 2026-10-08.
Reviewed by the MaterialWhiz Editorial Team. This estimate uses the assumptions shown in the calculator. Review the result against your supplier's product coverage and site conditions. Last reviewed: October 10, 2026. See how we calculate · Report a correction.