Shingle Calculator
Estimate shingle bundles, squares, underlayment, ridge caps, and nails - adjusted for roof pitch and waste.
Measured at the eaves from the ground - not along the slope.
Total of all ridge and hip lines, for ridge-cap bundles. Leave blank to skip.
Your Shingle Estimate
- Measure the footprint - building length × width from the ground, at the eaves.
- Select the pitch - this converts the flat footprint to true sloped roof area.
- Pick the shingle type - most asphalt shingles are 3 bundles per square.
- Enter ridge + hip length - for the ridge-cap bundle count; skip it if unknown.
- Read the material list - squares, bundles, underlayment, ridge caps, and nails to order.
Standard asphalt shingles - both 3-tab and architectural - cover 3 bundles per square, where a square is 100 sq ft of roof. So a 20 square roof takes 60 bundles before waste, and 66 to 69 once you add the usual 10 to 15 percent. Premium designer shingles run 4 bundles per square. The count on the wrapper always wins, so check it before ordering. Enter your footprint and pitch above for the full material list: bundles, underlayment, ridge caps, and nails.
What a Square of Shingles Looks Like
How Many Bundles of Shingles Do I Need?
Start with your roof footprint - length times width, measured from the ground at the eaves. Multiply by the pitch multiplier for your slope to get the true sloped area, divide by 100 for squares, add waste, then multiply by three for bundles (most asphalt shingles come three bundles to a square). This calculator does all of that and then keeps going, because shingles are only part of the order.
A complete roof also needs underlayment, ridge-cap shingles, and nails - the items that turn a pile of bundles into a watertight roof. This calculator estimates underlayment rolls from the roof area, ridge-cap bundles from your ridge and hip length, and nails from the squares, so you walk into the supply yard with one order sheet instead of guessing at the counter.
The Pitch Multiplier
A sloped roof has more surface than the flat footprint beneath it. Multiply the footprint by the factor for your pitch:
| Pitch | Slope | Multiplier | Area added |
|---|---|---|---|
| 2/12 | Low | 1.014 | +1.4% |
| 4/12 | Common | 1.054 | +5.4% |
| 5/12 | Common | 1.083 | +8.3% |
| 6/12 | Moderate | 1.118 | +11.8% |
| 8/12 | Steep | 1.202 | +20.2% |
| 12/12 | 45° | 1.414 | +41.4% |
Bundles per Square by Shingle Type
Coverage per bundle depends on the shingle. These are the typical counts - the bundle wrapper states the exact coverage for your product, and that number always wins:
| Shingle type | Bundles per square | Coverage per bundle | Bundle weight |
|---|---|---|---|
| 3-tab | 3 | About 33 ft² (roughly 29 shingles) | 50 to 65 lb |
| Architectural (laminated) | 3 | About 33 ft² (roughly 22 to 25 shingles) | 60 to 80 lb |
| Premium / designer | 4 | About 25 ft² | 70 to 90 lb |
| Cedar shakes (for comparison) | 4 to 5 | 20 to 25 ft² | Varies by cut |
This calculator covers asphalt shingles at 3 or 4 bundles per square. Heavier bundles matter for logistics too: a 30 square roof at 3 bundles per square is 90 bundles, which is 2 to 3 tons of material moving up a ladder.
Choosing the Waste Factor
Waste covers everything that gets cut and cannot be reused: the offcuts at rakes, valleys, hips, and around penetrations, plus a few damaged shingles per job. National Roofing Contractors Association guidance and standard estimating practice put it at about 10 percent for a simple gable roof, 12 to 15 percent where hips and valleys start adding diagonal cuts, and 15 to 20 percent for complex roofs with dormers, turrets, or many facets.
When in doubt, round up rather than down. An unopened bundle can usually be returned; a second delivery fee for two missing bundles cannot. If you are planning the whole job - underlayment weight, tear-off, and material comparisons - the roofing calculator works at the whole-roof level, while this page stays focused on the bundle math.
Ridge Caps, Starter Strip, and Nails
Ridge-cap shingles are sold by the linear foot of ridge and hip they cover, and coverage varies by brand more than field shingles do: GAF TimberTex and Owens Corning DecoRidge bundles cover about 20 linear feet, while CertainTeed Shadow Ridge covers about 33. This calculator uses 20 feet per bundle - the common case - so a brand with longer coverage simply leaves you a spare bundle.
Starter strip runs along the eaves and rakes under the first courses, so measure your roof perimeter edges and figure one bundle per roughly 100 linear feet. Nails come out to about 320 per square using 4 nails per shingle - 6 in high-wind zones - which is roughly 2.5 pounds of 1-1/4 inch roofing nails per square. The calculator scales both nails and underlayment from your roof area automatically.
The Full Material List
Beyond the shingle bundles, here is what the calculator estimates and the rule behind each:
| Material | Rule of thumb | Notes |
|---|---|---|
| Shingle bundles | 3 per square (4 for designer) | 33.3 ft² per bundle |
| Underlayment | 1 synthetic roll per 10 squares | Synthetic rolls ≈ 1,000 ft²; #15 felt ≈ 400 ft² |
| Ridge caps | 1 bundle per ~20 lin ft | Along ridges and hips; some brands cover ~33 ft |
| Nails | ≈320 per square (~2.5 lb) | 4 per shingle; 6 in high-wind zones |
| Starter strip | 1 bundle per ~100 lin ft | Eaves and rakes (see note) |
Bundle Counts by Roof Size (architectural, 10% waste)
| Footprint | Pitch | Squares | Bundles |
|---|---|---|---|
| 30 × 40 | 4/12 | 14.0 | 42 |
| 30 × 50 | 6/12 | 18.5 | 56 |
| 40 × 60 | 6/12 | 29.6 | 89 |
| 40 × 60 | 8/12 | 31.8 | 96 |
Squares include pitch and 10% waste. Bundles at 3 per square, rounded up.
Shingle Formulas
Footprint to true area to a full takeoff:
Squares = roof area ÷ 100, × (1 + waste)
Bundles = squares × bundles per square (3 standard), rounded up
Underlayment = roof area ÷ roll coverage (1,000 ft² synthetic), rounded up
Ridge caps = ridge + hip length ÷ 20 ft per bundle, rounded up
Nails = squares × ~2.5 lb (≈320 nails per square)
Pitch multiplier = √(1 + (rise/12)²). Codes may also require ice-and-water shield, drip edge, and ventilation not counted here.
Code Notes & Sources
- The 4 nails per shingle baseline comes from the residential code: asphalt shingles must get the fastener count the manufacturer requires, and never fewer than four fasteners per strip shingle. High-wind regions and steep slopes push that to six per the wrapper instructions.IRC 2021 Section R905.2 - Asphalt Shingles (R905.2.6 Attachment)
- Waste percentages follow National Roofing Contractors Association estimating guidance: roughly 10 percent on simple gables, rising to 15 to 20 percent as valleys, hips, and dormers multiply the diagonal cuts.National Roofing Contractors Association - Consumer Information
Next Steps
Bundle count in hand, close out the rest of the estimate:
Related Calculators
See the full construction calculator collection for pitch, area, and cost tools.
Frequently Asked Questions
How many bundles of shingles are in a square?
Three bundles cover one roofing square (100 square feet) for standard 3-tab and architectural shingles, since each bundle covers about 33.3 square feet. Heavy designer shingles can run four bundles per square. This calculator uses three by default and lets you switch to four.
How do I account for roof pitch?
Multiply your flat footprint by the pitch multiplier. A common 4/12 roof adds about 5.4% to the footprint area, while a steep 12/12 adds over 41%. The calculator applies this automatically when you select your pitch - if you do not know it, the Roof Pitch Calculator finds it from rise over run.
How much underlayment and how many nails do I need?
A standard synthetic underlayment roll covers about 1,000 square feet (10 squares), while #15 felt covers about 400 and #30 felt about 200 - pick your roll size in the calculator and it counts the rolls. For nails, plan on roughly 320 per square, which is about 2.5 pounds of 1-1/4 inch roofing nails, using four nails per shingle or six in high-wind zones.
How many ridge-cap bundles do I need?
Measure the total length of all ridge and hip lines in feet and divide by 20, since common ridge-cap bundles like GAF TimberTex and Owens Corning DecoRidge cover about 20 linear feet each (some CertainTeed bundles cover about 33). Enter that length in the calculator and it returns the count; leave it blank if you are only ordering field shingles for now.
What waste factor should I use for a roof?
About 10% for a simple gable roof, 12% for one with some hips and valleys, and 15% for a complex hip roof with many cuts and dormers. Valleys and steep pitches generate more offcuts, so the more complicated the roof, the higher the waste.
How many bundles of shingles do I need for a 1,000 / 1,500 / 2,000 / 2,400 sq ft roof?
At 3 bundles per square, 1,000 sq ft of roof takes 30 bundles, 1,500 takes 45, 2,000 takes 60, and 2,400 takes 72 - all before waste, so add 10 to 15 percent on top. Note these are roof surface areas, not house footprints: a sloped roof is bigger than the footprint under it, which is what the pitch selector corrects for.
How much does a bundle of shingles weigh?
A bundle of 3-tab shingles weighs about 50 to 65 pounds and a bundle of architectural shingles about 60 to 80, with heavy designer lines running higher. That adds up fast: a typical 20 square roof is 60-plus bundles, so plan delivery with a boom truck to the roofline rather than carrying two tons up a ladder.