เครื่องคำนวณหลังคา
Calculate roofing material needed in squares and bundles. Includes pitch factor and waste.
วิธีใช้เครื่องคิดเลขนี้
- ป้อนRoof Length (ft)
- ป้อนRoof Width (ft)
- ป้อนRoof Pitch (rise:run, e.g. 4)
- ป้อนWaste Factor (%)
- คลิกปุ่มคำนวณ
- อ่านผลลัพธ์ที่แสดงด้านล่างเครื่องคิดเลข
Understanding Roofing Squares
Roofing is measured in "squares" — 1 square = 100 square feet of roof surface. For a 2,000 sq ft roof area, you need 20 squares of material. Each square of standard shingles requires 3 bundles (about 29 shingles per bundle).
The actual roof area is larger than the footprint due to roof pitch. A roof with a 6:12 pitch covers 1.12× more area than a flat projection.
Calculating Roof Pitch Factor
Pitch is expressed as rise:run (inches of rise per 12 inches of run). Pitch factor = √(1 + (pitch/12)²). Common pitch factors:
3:12 pitch: 1.031×. 4:12: 1.054×. 6:12: 1.118×. 8:12: 1.202×. 12:12: 1.414×.
A 6:12 roof over a 1,000 sq ft footprint has 1,118 sq ft of actual surface area — 11.8% more than the flat measurement.
Roofing Material Quantities
Standard asphalt shingles: 3 bundles per square, ~240 shingles per square. For underlayment: 1 roll per 4 squares. Starter strips: linear feet of eaves + rakes. Ridge cap: linear feet of ridge ÷ 35 per bundle.
Always add 10–15% waste for standard roofs, 15–20% for complex roofs with multiple valleys, hips, or dormers.
อัปเดตล่าสุด: March 2026
Frequently Asked Questions
How many bundles of shingles do I need for a 2000 sq ft house?
A typical 2000 sq ft house has a roof footprint of about 2000 sq ft. With a 6:12 pitch, actual roof area = 2000 × 1.118 = 2236 sq ft = 22.4 squares. Add 10% waste = 24.6 squares ≈ 74 bundles.
What is a roofing square?
One roofing square equals 100 square feet of roof surface. It's the standard unit for roofing material estimates. Shingles typically come 3 bundles per square.
How do I measure roof pitch?
Place a level horizontally on the roof. At the 12-inch mark from one end of the level, measure vertically from the level down to the roof surface. That measurement is the rise; the run is 12. A 4-inch rise = 4:12 pitch.