How Many Shingles Do I Need?
From roof area to squares and bundles, with waste, starter strips and ridge caps
How many shingles you need
Shingles are sold by the bundle, so the answer is a bundle count: bundles = roof surface area ÷ 100 × bundles per square, plus a waste allowance. Most 3-tab and architectural shingles come 3 bundles to the square, so a 1,342 ft² roof is 13.42 squares and 40.3 bundles exact, or 44.3 with 10% waste. Bundles are bought whole, so that rounds up to 45.
The Roof Shingle Calculator does this arithmetic and keeps the exact squares separate from the order quantity. Starter strips and hip/ridge caps either come out of the waste allowance or are ordered as separate products, as explained below. For underlayment, drip edge and the rest of the material list, use the Roofing Calculator.
Start with roof area, not footprint
Shingle calculations start from the true sloped roof area (footprint × slope factor), not the building's flat footprint. Using the footprint alone under-orders material for anything but a flat roof.
The slope factor for each pitch is listed in the roof pitch chart; a 6/12 roof, for example, has about 11.8% more surface than its plan. The guide to calculating roof area and the Roof Area Calculator cover the measurements.
Overhangs are shingled too, so for a shingle order measure the plan to the outside of the eaves and rakes rather than to the walls. The 1,342 ft² example on this page is the roof area guide's 30 ft × 40 ft plan with no overhang; with 1 ft overhangs all round, the plan becomes 32 ft × 42 ft and the roof about 1,503 ft², as Roof Area vs Floor Area shows. That is 15.03 squares, or 50 bundles with 10% waste instead of 45.
Roofing 'squares'
Roofing is priced and ordered in squares — one square covers 100 square feet of roof. Divide the roof area by 100 to get the number of squares: 1,342 ft² of roof is 13.42 squares.
Bundles per square
Bundles per square = 100 ÷ the coverage of one bundle. Most popular shingles are packaged so that three bundles cover a square — about 33.3 ft² a bundle — which is why 3 bundles per square is the usual default. The Asphalt Roofing Manufacturers Association's residential manual says there are typically 3, 4 or 5 bundles per square, depending on the product.
| Coverage per bundle | Bundles per square | IKO example (product-specific) |
|---|---|---|
| 33.3 ft² | 3 | Cambridge, Royal Estate (laminated) |
| 25 ft² | 4 | Crowne Slate |
| 20 ft² | 5 | Armourshake |
Why not every product is 3 bundles per square
Bundles per square is a packaging choice, not a fixed rule: even IKO's Marathon Plus AR 3-tab covers 32.3 ft² a bundle, or 3 bundles plus 2 shingles per square. Enter the figure from the wrapper in the calculator.
Add waste for cuts and hips/valleys
Shingles are trimmed at rakes, valleys, hips and around penetrations, so the order is larger than the exact squares. ARMA's manual puts trim waste for most jobs at 2–10%, depending on how many valleys, dormers, hips and penetrations the roof has, and IKO gives about 10–15% as a general range, noting that smaller roofs tend to waste a larger share.
Apply the allowance to the exact bundle count, then round up once to whole bundles: the exact squares stay as measured, and only the order goes up. The Roof Shingle Calculator rounds the same way.
| Roof | Allowance to start from | Basis |
|---|---|---|
| Simple gable, few penetrations | 10% | Calculator default; includes starter and caps cut from field shingles |
| Hips, valleys or dormers | 12–15% | Estimate from common practice; not an ARMA or manufacturer figure |
| Small or heavily cut-up roof | Upper end of the range or more | Smaller roofs tend to waste more (IKO) |
Starter strips and ridge caps
The first course along the eaves sits on a starter strip, and hips and ridges are finished with cap shingles. ARMA's manual allows the starter to be field shingles trimmed to the manufacturer's recommendations, a strip of mineral-surfaced roll roofing, or pre-cut starter shingles, and IKO notes that caps can be cut from field shingles or bought as dedicated caps. Which of these a given shingle needs, and where starter goes, is set by that product's installation instructions, so check them before choosing a method.
Cut from field shingles
Where the manufacturer allows it, this is what the Roof Shingle Calculator assumes: its single waste allowance (10% by default) covers the trimming waste and the starter and hip/ridge pieces cut from field bundles, so nothing is added separately.
Dedicated starter and hip/ridge products
If the instructions call for purpose-made starter or cap shingles, or you choose them, order them by length in addition to the field bundles: starter along the eaves, plus the rakes where the instructions require it (IKO's estimate counts both), and cap along every hip and ridge. Divide each length by the product's coverage per bundle and round each product up to whole bundles on its own. Coverage varies widely: IKO lists 123 linear ft per bundle for its Leading Edge Plus starter, 20 ft for its Ultra HP hip and ridge caps and 36.5 ft for its Hip & Ridge 12. Don't raise the field waste allowance to cover them as well.
Worked Example
A 1,342 ft² simple gable roof — the roof area guide's 30 ft × 40 ft plan at 6-in-12, with no overhang included — 10% waste and 3 bundles per square.
Squares (exact): 1,342 ÷ 100 = 13.42 squares
Bundles (exact): 13.42 × 3 = 40.26 bundles
With 10% waste: 13.42 × 1.10 ≈ 14.76 squares = 44.29 bundles
Order: round 44.29 up to 45 whole bundles
Dedicated starter, if used: eaves 2 × 40 = 80 ft, plus rakes 4 × (15 × 1.118) ≈ 67.1 ft, = 147.1 ft; ÷ 123 ft per bundle (IKO Leading Edge Plus) = 1.2 → round up to 2 bundles, or 1 bundle if starter goes on the eaves only (80 ÷ 123 = 0.65)
Dedicated ridge cap, if used: 40 ft of ridge ÷ 20 ft per bundle (IKO Ultra HP) = 2.0 → 2 bundles; the field order stays 45 bundles
Assumptions & Limitations
- Bundle-per-square counts vary by manufacturer and shingle type — confirm against the specific product's packaging.
- Waste allowances are starting points from common estimating practice; a roofer's takeoff from the actual roof is more precise.
- The worked example includes no overhang; overhangs also lengthen the eave, rake and ridge runs used for starter and caps.
- IKO coverage figures are product-specific examples; use the figures for the product you buy.
- Underlayment, drip edge, flashing, nails and vents are estimated separately.
FAQ
- How many bundles of shingles do I need for 1,000 square feet?
- At 3 bundles per square, 1,000 ft² of roof is 10 squares and 30 bundles exact, or 33 bundles with a 10% waste allowance (30 × 1.10 = 33, already a whole number; otherwise round up). Use the sloped roof area including overhangs, not the floor area, and check the bundles per square on your product.
- How many square feet does a bundle of shingles cover?
- Most popular shingles are packaged so that 3 bundles cover a 100 ft² square, or about 33.3 ft² a bundle. Some heavier products cover less: IKO lists one line at 25 ft² a bundle (4 per square) and another at 20 ft² (5 per square). The coverage is printed on the bundle.
- How much waste should I add for shingles?
- ARMA puts trim waste for most jobs at 2–10%, and IKO gives about 10–15% as a general range, with smaller roofs tending to waste more. This guide and the calculator start from 10% for a simple gable and 12–15% for a roof with hips and valleys; those are estimates, not ARMA or manufacturer figures.
- Do I need to buy starter strips and ridge caps separately?
- It depends on the shingle's installation instructions. If they allow starter and caps cut from field shingles, the waste allowance covers those pieces. If they call for dedicated starter or hip and ridge cap products, order them by length on top of the field bundles — starter along the eaves (and the rakes where required), caps along every hip and ridge.
- Does roof pitch change how many shingles I need?
- Yes, through the roof area. A steeper roof has more surface over the same footprint: a 6/12 roof is about 11.8% larger than its plan and a 12/12 roof about 41.4% larger. Apply the slope factor to the plan area before converting to squares.
Related Calculators
Related Guides
From the Blog
Sources
ARMA Residential Asphalt Roofing Manual (2014 edition)
1 square = 100 ft²; typically 3, 4 or 5 bundles per square; trim waste of 2–10% for most jobs; starter strip options.
ARMA Residential Asphalt Roofing Manual (2014 edition) — referenceIKO, How Many Shingles in a Bundle?
Product-specific coverage per bundle (approximate, per IKO); about 10–15% general waste range; starter length from eaves and rakes; hip and ridge cap coverage.
IKO, How Many Shingles in a Bundle? — reference