Roof Shingle Calculator
Reviewed by the My Roof Pitch editorial team · Updated · Free, no sign-up, works offline after first load
Shingle quantity is roof area divided by 100 to get squares, plus waste, times three bundles per square. A 2,000 sq ft roof with 10% waste needs 22 squares, which is 66 bundles of standard three-tab or architectural shingles.
Your measurements
Enter the values you know — results update live.
Length × width of the building on plan, including overhangs.
Used to convert the footprint into true sloped area.
10% for a simple gable, 15% or more with hips and valleys.
Analysis
Live results from your measurements.
Show the working
- Sloped area:
1,500 × 1.118= 1,677 sq ft - Squares:
1,677 ÷ 100= 16.77 - With waste:
16.77 × 1.1= 18.45 - Bundles:
ceil(18.45 × 3)= 56 - Nails:
18.45 × 320= 5904 - Underlayment:
1,677 ÷ 1,000= 2
What this calculator does
Asphalt shingles are sold in bundles, and three bundles cover one square — 100 square feet of finished roof. Ordering starts from the true sloped area, not the footprint, then adds a waste allowance for starter courses, cut-offs at hips and valleys, and damaged pieces. Two items sit outside the square count: starter strip along every eave and rake, and ridge cap along every ridge and hip. Both are sold by the linear foot, and both get missed regularly on first orders.
How to use it
- Calculate the sloped roof area by multiplying the footprint by the pitch multiplier.
- Divide by 100 to convert to roofing squares.
- Add a waste allowance of 10% to 20% depending on how cut-heavy the roof is.
- Multiply the result by three to get the bundle count for standard shingles.
- Measure total eave length for starter strip and total ridge plus hip length for cap shingles.
- Round every quantity up to whole bundles — suppliers do not split them.
The formula
Squares needed
squares = (footprint × pitch multiplier / 100) × (1 + waste)
The core quantity every other number is derived from.
Bundle count
bundles = ceil(squares × 3)
Three bundles per square for three-tab and architectural shingles.
Nail count
nails = squares × 320
Roughly 320 nails per square using four nails per shingle; six-nail high-wind patterns need about 480.
Worked example
A 1,600 sq ft footprint with a 7:12 hip roof, 15% waste, 140 ft of eave, 70 ft of ridge and hip, and synthetic underlayment covering 1,000 sq ft per roll.
- Multiplier for 7:12: 1.1577
- Sloped area: 1,600 × 1.1577 = 1,852 sq ft
- Squares: 18.52 × 1.15 = 21.3
- Bundles: 21.3 × 3 = 64
- Starter: 140 ÷ 105 = 2 bundles; ridge cap: 70 ÷ 20 = 4 bundles
- Underlayment: 1,852 ÷ 1,000 = 2 rolls
64 bundles of field shingles, 2 bundles of starter, 4 bundles of ridge cap and 2 rolls of underlayment.
Reference chart
| Sloped area (sq ft) | Squares | Squares with waste | Bundles |
|---|---|---|---|
| 1000 | 10 | 11 | 33 |
| 1500 | 15 | 16.5 | 50 |
| 2000 | 20 | 22 | 66 |
| 2500 | 25 | 27.5 | 83 |
| 3000 | 30 | 33 | 99 |
| 4000 | 40 | 44 | 132 |
Shingle type coverage and expected service life
| Shingle type | Bundles per square | Weight per square | Typical life |
|---|---|---|---|
| Three-tab asphalt | 3 | 200–240 lb | 15–20 years |
| Architectural / laminated | 3 | 240–340 lb | 25–30 years |
| Designer / luxury asphalt | 4–5 | 400–480 lb | 30–50 years |
| Cedar shake (medium) | 4–5 | 300–400 lb | 25–40 years |
| Synthetic composite | 3–4 | 180–250 lb | 40–50 years |
Common mistakes
- Ordering against the footprint rather than the sloped area.
- Forgetting starter strip and ridge cap, which are separate products from field shingles.
- Using 10% waste on a hip roof. Every hip is a full run of angled cuts.
- Mixing bundles from different production lots, which can show as colour banding across the roof.
- Assuming three bundles per square for heavyweight designer shingles — those run four or five.
- Buying exactly the calculated count with no spare bundle for future repairs.
Assumptions and limits
- Three bundles per square unless the product says otherwise.
- Starter strip covers about 105 linear feet per bundle, ridge cap about 20 to 25 linear feet.
- Nail counts assume a four-nail pattern; high-wind zones require six.
- Underlayment roll coverage is user-adjustable; defaults to 1,000 sq ft for synthetic underlayment.
- Quantities exclude ice and water shield, drip edge and flashing.
Frequently asked questions
How many bundles of shingles do I need for a 2000 square foot roof?
A 2,000 square foot roof is 20 squares. With a 10% waste allowance that is 22 squares, which needs 66 bundles of standard three-tab or architectural shingles.
How many shingles are in a bundle?
A bundle of three-tab shingles holds 26 pieces and covers 33.3 square feet. Architectural bundles hold 21 to 24 larger pieces and cover the same 33.3 square feet.
How much do shingles weigh?
A square of three-tab shingles weighs 200 to 240 pounds, architectural 240 to 340 pounds. That is 65 to 115 pounds per bundle, which matters for both delivery and deck loading.
How many nails per square of shingles?
About 320 nails per square with the standard four-nail pattern, or roughly 480 with the six-nail high-wind pattern. That works out to 2 to 3 pounds of roofing nails per square.
Do I need starter shingles?
Yes. Starter strip seals the first course and provides the adhesive line that resists wind uplift at the eave. Cut-up field shingles are not an approved substitute under most warranties.
How much extra should I buy?
Keep one full bundle beyond the calculated total. Colour lots change over time, so a matching spare bundle is far easier to store now than to source in five years.
Related guides
- Common Roof Pitches Explained: 3:12 Through 12:12A pitch-by-pitch breakdown of every slope you will meet on a house — what each one costs, what it can be covered with, and which climates it suits.
- Roofing Squares and Shingle Bundles: How Many You NeedThe estimating unit every roofer quotes in — plus the starter strip, hip and ridge cap, underlayment and nail quantities that never appear in the headline square count.
- Roof Replacement Cost: How Roofing Quotes Are Actually BuiltRoofers price per square, not per square foot of house. Here is how material, labour, tear-off, steepness and access combine into the number on your quote — and where the extras hide.
Last updated 2026-08-05. Results are estimates for planning and are not a substitute for a licensed engineer or local code review.