Roof Shingles Calculator — m, m², bundles, cost
How to use this calculator
Pick an input method: enter the slope-adjusted roof area directly in m², enter footprint length and width and let the pitch factor scale it, or list each roof plane under Sections. Choose the shingle product, set a waste allowance for cuts and starter courses, then toggle underlayment, starter strip, ridge cap, drip edge, nails, and cost. Estimates follow asphalt-shingle manufacturer coverage data and EN 14783 roofing practice.
Pitch — select the roof angle in degrees (0° to 45°). Higher pitch = more actual roof area.
Shingle types — 3-Tab (3 bundles/square), Architectural (3-4), Premium (4-5). 1 square = 9.29 m².
Cost — enter price per bundle, per underlayment roll, per ridge bundle, and per drip edge piece. Select your currency below.
Saved Calculations
| Time | Method | Area m² | Squares | Bundles | Cost |
|---|
How to Calculate Roof Shingles (Metric)
Asphalt shingles are sold by the bundle, and the trade still orders by the square (9.29 m² of finished roof). Three bundles cover one square for most 3-tab and architectural products; heavy designer shingles run four. The order is driven by the slope-adjusted roof area and a waste allowance: about 10% for a simple gable, 15% for an average roof, and 15–25% when hips, valleys, dormers and short courses force many cut shingles.
How to use it
If you already know the true roof area from a roof area and pitch calculator, enter it on the Area tab — it is already slope-adjusted. Otherwise use Dimensions (footprint length × width) or Sections for multi-plane roofs and let the pitch factor scale the footprint. Toggle the accessory cards for underlayment, starter, ridge cap, drip edge and nails, then open Cost and pick a currency for a priced bill of materials.
Shingle coverage and pitch factor
One square = 9.29 m². Pitch multiplies plan area by 1/cos(angle): an 18° (≈4:12) roof is 1.054×, 27° (6:12) is 1.118×, 34° (8:12) is 1.202×, and 45° (12:12) is 1.414×. Steeper roofs both add area and push waste toward the high end. For very low-slope sections consider a flat roof membrane calculator instead of shingles.
Formulas used
Adjusted area = footprint area × pitch factor. Squares = adjusted area / 9.29 m². Bundles = ⌈squares × bundles/square × (1 + waste%)⌉. Underlayment rolls = ⌈adjusted area × (1 + overlap%) / roll coverage⌉. Starter ≈ eave+rake m / 32. Ridge cap ≈ ridge+hip m / 6. Drip edge = ⌈perimeter m / 3⌉ pieces. Nails ≈ 80 per bundle at roughly 3.4 kg per 1,000.
Related calculators
Pair this estimate with a gutter and downspout calculator for the eave run, compare a standing-seam alternative with the metal roofing calculator, get the true surface area from a roof area and pitch calculator, check rafters and deck framing with the lumber volume calculator and size the deck with the deck calculator.
Ordering tips
In 2025 a tear-off and replace with architectural shingles runs roughly €45–80/m² installed, €35–55/m² for 3-tab, and €85–150/m² for premium designer. Materials alone are typically €15–25/m². The most common estimator mistake on shingle jobs is forgetting drip edge and starter: drip edge at eaves and rakes is required by EN 14783 best practice, and a factory starter strip at the eave is required by every major manufacturer's warranty. Order the starter and ridge-cap product separately — never cut them from field bundles. For complex hip roofs jump waste to 18–22%, and remember that valleys, dormers, and roof windows each push you closer to the next full bundle. In cold climates add a self-adhesive ice-and-water membrane at least 600 mm inside the warm wall — count it on top of the underlayment rolls for those eave courses.
FAQ
Do I subtract for ridge and hips? No — order full field bundles for the whole roof area, then add separate starter and ridge-cap bundles cut from dedicated hip/ridge product.
How many nails? Codes typically require 4 nails per shingle (6 in high-wind zones); this tool assumes ~80 per bundle.
Is the area tab slope-adjusted? Yes — enter the true surface area there. Only Dimensions and Sections apply the pitch factor.
