屋顶坡度计算器 — 角度、坡率 & 屋顶面积
输入屋顶测量值，即时在坡度（X:12）、角度（度）和坡率百分比之间换算。可选输入屋顶平面面积，计算实际斜面面积，用于订购屋顶板材和其他材料。支持通过高差和水平距离、角度或直接输入坡度来计算。
Roof Pitch Calculator
Calculate roof pitch, angle, slope percentage, and actual roof area
Frequently Asked Questions
屋顶坡度计算器是如何工作的？
屋顶坡度（坡比）通常以"X in 12"表示，即水平方向每延伸 12 英寸，垂直方向上升 X 英寸。计算器支持在坡比、角度（度）和百分比坡度之间相互换算，并可计算实际斜面长度和屋顶面积。
不同屋顶坡度有什么特点？
低坡屋顶（< 3/12，约 14°）：排水较差，适合平屋顶专用材料；中坡（4/12-6/12，18-27°）：最常见，适合沥青瓦；高坡（7/12-12/12，30-45°）：排水优秀，适合多种屋面材料，但施工难度和成本更高；超高坡（> 12/12，> 45°）：主要用于装饰性元素。
如何测量现有屋顶的坡度？
使用坡度仪（坡度水平仪）：将 12 英寸长的水平仪水平放置，一端紧贴屋面，测量另一端到屋面的垂直距离即为"X"。或使用智能手机水平仪 App 直接测量屋面角度。
屋顶坡度如何影响所需材料量？
坡度越大，实际斜面面积与建筑平面投影面积之比越大，称为屋顶系数（Roof Pitch Factor）。4/12 坡度系数约 1.054，6/12 约 1.118，12/12 约 1.414。将平面面积乘以坡度系数即得斜面实际面积，用于计算屋面材料用量。
Roof Pitch Calculator: Angle, Slope & Area Guide
This roof pitch calculator converts between pitch (X:12), angle (degrees), and slope percentage. It also calculates the area multiplier for estimating actual roof surface area from a floor plan footprint.
What is Roof Pitch?
Roof pitch is the measure of a roof's steepness, expressed as the ratio of vertical rise to horizontal run. In the United States, pitch is typically given in the X:12 format, where X is the number of inches the roof rises for every 12 inches of horizontal run. A 4:12 pitch means the roof rises 4 inches for every foot of horizontal distance.
Roof pitch affects drainage, aesthetics, material choices, and construction cost. Steeper roofs shed water and snow better but require more materials and labor. Shallow roofs are cheaper to build but may need special waterproofing membranes.
Roof Pitch Formula
Pitch (X:12)
Angle (degrees)
Slope Percentage
Area Multiplier (Hypotenuse Factor)
Multiply your floor plan area by this factor to get the actual sloped roof surface area.
Common Roof Pitches
| Pitch (X:12) | Angle | Slope % | Multiplier | Category |
|---|---|---|---|---|
| 1:12 | 4.76° | 8.3% | 1.0035 | Low |
| 2:12 | 9.46° | 16.7% | 1.0138 | Low |
| 3:12 | 14.04° | 25.0% | 1.0308 | Low |
| 4:12 | 18.43° | 33.3% | 1.0541 | Low |
| 5:12 | 22.62° | 41.7% | 1.0833 | Medium |
| 6:12 | 26.57° | 50.0% | 1.1180 | Medium |
| 7:12 | 30.26° | 58.3% | 1.1577 | Medium |
| 8:12 | 33.69° | 66.7% | 1.2019 | Medium |
| 9:12 | 36.87° | 75.0% | 1.2500 | Medium |
| 10:12 | 39.81° | 83.3% | 1.3017 | Steep |
| 12:12 | 45.00° | 100.0% | 1.4142 | Steep |
| 14:12 | 49.40° | 116.7% | 1.5366 | Steep |
How to Measure Roof Pitch
Method 1: Using a Level and Tape Measure
- Hold a 12-inch level horizontally against the roof slope.
- Measure 12 inches along the level from where it touches the roof surface.
- At that 12-inch mark, measure straight down to the roof surface.
- That vertical measurement (in inches) is your pitch number.
Method 2: From the Attic
- Enter the attic and hold a level horizontally against a rafter.
- Measure 12 inches horizontally along the level from the rafter.
- Measure vertically from that point up to the rafter.
- That vertical measurement is your pitch in the X:12 format.
Roof Area Formula
The actual sloped roof area is larger than the horizontal footprint. Use the area multiplier to convert from footprint area to actual roof surface area, which is essential for ordering shingles, underlayment, and other roofing materials.
Multiplier for 6:12 = √(6² + 12²) / 12 = √180 / 12 ≈ 1.118
Actual Roof Area = 1,500 × 1.118 = 1,677 ft²
Shingles are sold by the "square" (100 ft²). For this example, you would need 17 squares, plus 10% waste = 19 squares.
Building Code Considerations
- Minimum pitch for asphalt shingles: 2:12 (with special low-slope installation), 4:12 recommended.
- Minimum pitch for metal roofing: 3:12 for standing seam, varies by product.
- Flat roofs (below 2:12) require built-up roofing (BUR) or TPO/EPDM membranes.
- Snow load considerations: In high-snow areas, steeper pitches (6:12+) help shed snow and reduce structural load.
- Local codes vary — always consult your local building authority before starting a roofing project.
- HOA restrictions may limit the range of acceptable pitch in some communities.
Related Tools
- Concrete Calculator — estimate concrete volume and bag counts for foundations, slabs, and columns.
- Aspect Ratio Calculator — calculate width-to-height ratios for screens, images, and architectural elements.