How to measure roof pitch (slope) angle
If you have a roof photo, a plan, or a construction drawing, you can measure the pitch angle in the browser.
When this helps
Use this when you need the roof slope angle in degrees (for checks, estimates, or documentation). The key is a clean reference baseline: true horizontal on a plan, or a level edge in a photo.
Step-by-step
- 1Get a clean roof viewUse a plan/blueprint when possible. For photos, try to capture the roof from the side (a clear profile) and avoid perspective tilt.
- 2Upload or paste the imageOpen the tool and add the image (upload, drag & drop, or paste).
- 3Align the horizontal baselineRotate/flip and use the grid to make a known horizontal line straight (e.g., a level beam, roof edge, or plan axis).
- 4Place the vertex and follow the slopeMove the center to the point where the slope starts (intersection). Align the baseline to horizontal, then rotate to match the roof slope line.
- 5Read the angle and exportUse snap for clean values, or fine-tune with snap off. Export PNG/PDF to document the pitch angle.
Tips
- Photos can lie: if the camera isn’t perpendicular to the roof face, perspective can bias the angle. A plan/blueprint is often more reliable.
- Always align first. A slightly tilted baseline can shift the pitch reading by several degrees.
- Zoom in when placing the vertex and lining up the slope edge. Small offsets matter.
Related
Measure an angle on a blueprint
If you have plans, measuring pitch from a blueprint is usually the most stable method.
Measure an angle from a camera photo
When you only have an on-site photo, use the camera workflow and focus on alignment.
PNG and PDF exports
Save a shareable image or a report once the pitch angle is correct.
Angle looks inaccurate
Common causes: perspective distortion, baseline misalignment, and vertex placement.