CalcOpenly
Bahasa Indonesia

Roofing and shingle calculator

Roof area, squares and shingle bundles from building size and pitch, with underlayment rolls, ridge cap and the IRC minimum slope check.

Diperbarui Contoh terverifikasi: 4

in 12
%
Opsi lainnya
Three bundles cover one square (100 ft²) for most 3-tab and architectural shingles.
Read it on the wrapper: GAF Seal-A-Ridge covers about 25 ft, Owens Corning ProEdge about 33 ft.
Coba
Shingle bundles to buy
bundles
Shingle bundles to buy: 50 bundles
Bilangan bulat; Menuju positif tak hingga
Roof area
1,502.6ft² / 139.6m²
Squares with waste
16.53squares
Underlayment rolls
4rolls
Ridge and hip length
42.0ft / 12.8m
Ridge cap bundles
2bundles
Pitch angle
26.6°
Slope factor
1.1180

The roof surface is 1,503 ft² (139.6 m²), which with 10% waste is 16.53 squares: 50 bundles of shingles, 4 rolls of #15 felt and 2 bundles of ridge cap for 42 ft of ridge.

Roof cross-section

32 ft (9.75 m) with overhangsrise 8 ft (2.44 m)rafter 17.89 ft (5.45 m)26.6°
Cara menghitung S

  1. Footprint with overhangs

    (40+2×1)(30+2×1)=1,344 ft2(40 + 2 \times 1)(30 + 2 \times 1) = 1{,}344\ \text{ft}^2

  2. Slope factor

    1+0.52=1.11803\sqrt{1 + 0.5^2} = 1.11803

    Pitch 6 in 12 = 26.57°. A hip roof with the same pitch on all four sides has the same area factor.

  3. Roof area

    1,344×1.11803=1,502.638 ft21{,}344 \times 1.11803 = 1{,}502.638\ \text{ft}^2

  4. Squares and bundles

    1,502.638×1.1100=16.529 squares×3⇒50 bundles\frac{1{,}502.638 \times 1.1}{100} = 16.529\ \text{squares} \times 3 \Rightarrow 50\ \text{bundles}

    Rounded up to whole bundles.

  5. Underlayment

    ⌈15.0264⌉=4 rolls\left\lceil \frac{15.026}{4} \right\rceil = 4\ \text{rolls}

    Roll coverage already allows for laps; rounded up to whole rolls.

  6. Ridge

    ridge=42 ft\text{ridge} = 42\ \text{ft}

    Ridge cap: 42 ft ÷ 25 ft per bundle, rounded up to 2.

Tentang Roofing and shingle calculator

Roof area is the footprint including overhangs multiplied by the slope factor √(1 + (rise ÷ 12)²), which turns plan area into sloped surface. A hip roof with the same pitch on all four sides has the same factor as a gable. Area plus waste is divided into squares of 100 ft² and multiplied by bundles per square; the ridge and hip length divided by the coverage of one ridge-cap bundle gives the ridge bundles.

The default 40 × 30 ft gable with 1 ft overhangs at a 6/12 pitch has a slope factor of 1.118 and 1,502.64 ft² of roof. With 10% waste that is 16.53 squares, or 50 bundles at three per square, plus 4 rolls of #15 felt and 2 bundles of ridge cap.

The pitch is checked against the asphalt-shingle slope rules in 2021 IRC R905.2.2. Valleys, dormers, starter strip and drip edge are not counted.

Contoh penyelesaian

40 × 30 ft gable, 1 ft overhang, 6/12, 10% waste

Roof type
Gable
Building length
40 ft
Building width
30 ft
Overhang on each side
1 ft
Pitch given as
Rise per 12
Pitch
6 in 12
Waste allowance
10%
Underlayment
#15 felt (4 squares per roll)
Roof area
1,502.6 ft²
Squares with waste
16.53 squares
Shingle bundles to buy
50 bundles
Underlayment rolls
4 rolls
Ridge and hip length
42.0 ft
Ridge cap bundles
2 bundles
Pitch angle
26.6 °

Sumber pemeriksaan: Python decimal: 42 × 32 × √1.25 = 1502.64 ft²; × 1.1 ÷ 100 × 3 = 49.59 → 50 bundles; 15.03 squares ÷ 4 → 4 rolls

Hip roof 40 × 30 ft, 6/12, no overhang or waste

Roof type
Hip
Building length
40 ft
Building width
30 ft
Overhang on each side
0 ft
Pitch given as
Rise per 12
Pitch
6 in 12
Waste allowance
0%
Underlayment
#15 felt (4 squares per roll)
Roof area
1,341.6 ft²
Ridge and hip length
100.0 ft
Shingle bundles to buy
41 bundles

Sumber pemeriksaan: Hand calculation: ridge 40 − 30 = 10 ft; each hip √(2 × 15² + 7.5²) = 22.5 ft, × 4 = 90 ft; 1200 × 1.118034 = 1341.64 ft²

Edge: 12/12 pitch is 45°

Roof type
Gable
Building length
30 ft
Building width
20 ft
Overhang on each side
0 ft
Pitch given as
Rise per 12
Pitch
12 in 12
Waste allowance
0%
Underlayment
#15 felt (4 squares per roll)
Roof area
848.5 ft²
Pitch angle
45.0 °
Slope factor
1.4142
Shingle bundles to buy
26 bundles

Sumber pemeriksaan: Hand calculation: slope factor √2 = 1.41421; 600 × √2 = 848.53 ft² → 25.46 → 26 bundles

30° roof on a 10 × 8 m house, 0.5 m overhang

Roof type
Gable
Building length
10 m
Building width
8 m
Overhang on each side
0.5 m
Pitch given as
Derajat
Pitch angle
30 °
Waste allowance
10%
Underlayment
#15 felt (4 squares per roll)
Roof area
114.32 m²
Shingle bundles to buy
41 bundles

Sumber pemeriksaan: Python math: 11 × 9 m ÷ cos 30° = 114.3154 m² = 1230.48 ft² × 1.1 ÷ 100 × 3 = 40.6 → 41

Pertanyaan

How many bundles of shingles do I need?

Divide the roof area by 100 to get squares, add waste, and multiply by the bundles per square printed on the wrapper (three is the default here). A 40 × 30 ft gable with 1 ft overhangs at 6/12 has 1,502.64 ft² of roof, or 16.53 squares with 10% waste: 49.6 bundles, bought as 50. The waste presets are 10% for gables and 15% for hips, where every course is cut along the hips.

How do you convert roof pitch to degrees and a slope factor?

Pitch is the rise in inches per 12 in of run. A 6/12 roof rises at arctan(6 ÷ 12) = 26.57°, and its slope factor √(1 + 0.5²) = 1.118 means each square foot of plan carries 1.118 ft² of roof. A 4/12 roof is 18.43° with a factor of 1.054; a 12/12 roof is 45° with a factor of 1.414.

What is the minimum roof pitch for asphalt shingles?

2:12, about 9.5°. Under 2021 IRC R905.2.2, asphalt shingles may be used only on slopes of 2 in 12 or steeper, and slopes from 2:12 up to 4:12 need double underlayment. Flatter roofs need a low-slope covering such as a membrane. In the 2:12 to 4:12 range this calculator doubles the underlayment rolls.

What is a roofing square?

100 ft² of roof surface, about 9.29 m². Shingles and underlayment are ordered by the square, so a roof of 1,502.64 ft² is 15.03 squares before waste and 16.53 after 10% waste. With the #15 felt option at 4 squares per roll, that roof takes 4 rolls of underlayment.

How do you calculate the area of a hip roof?

Use the same slope factor as a gable: when all four sides share one pitch, sloped area = plan area × √(1 + (rise ÷ 12)²). A 40 × 30 ft hip roof at 6/12 with no overhang is 1,200 × 1.118 = 1,341.64 ft². Its ridge is 40 − 30 = 10 ft and each of the four hips is 22.5 ft, so ridge cap covers 100 ft.

Seberapa akurat “Roofing and shingle calculator”?

Akurasi bergantung pada masukan dan asumsi metode. Aritmetika desimal memakai 50 digit signifikan, tetapi perkiraan, metode numerik dan data sumber bisa kurang presisi; pembulatan yang ditampilkan tidak menghilangkan batasan itu. Contoh penyelesaian yang diperiksa dengan sumber independen: 4. Misalnya, “40 × 30 ft gable, 1 ft overhang, 6/12, 10% waste” diperiksa dengan Python decimal: 42 × 32 × √1.25 = 1502.64 ft²; × 1.1 ÷ 100 × 3 = 49.59 → 50 bundles; 15.03 squares ÷ 4 → 4 rolls.

Dari mana metode ini berasal?

International Code Council — 2021 IRC R905.2.2: asphalt shingles on slopes of 2:12 or steeper, double underlayment from 2:12 up to 4:12; GAF Seal-A-Ridge — 25 linear ft per bundle; Owens Corning ProEdge — 33 linear ft per bundle.

Tentang kalkulator ini

A=(L+2o)(W+2o)1+(p/12)2,bundles=⌈3⋅A(1+waste)100⌉A = (L + 2o)(W + 2o)\sqrt{1 + (p/12)^2},\qquad \text{bundles} = \left\lceil 3 \cdot \frac{A (1 + \text{waste})}{100} \right\rceil

Sumber

  1. International Code Council — 2021 IRC R905.2.2: asphalt shingles on slopes of 2:12 or steeper, double underlayment from 2:12 up to 4:12
  2. GAF Seal-A-Ridge — 25 linear ft per bundle; Owens Corning ProEdge — 33 linear ft per bundle

Diperiksa dengan referensi

Kalkulator ini mencakup 4 contoh perhitungan dengan jawaban dari sumber independen. Contoh tersebut dijalankan dalam rangkaian pengujian dan dapat Anda jalankan di sini juga.

Kalkulator terkait