Building Code & Architecture

Stair Stringer Incline & Angle Measurement

Calculate stair incline angle degrees from step rise and run. Ensure IRC building code compliance (30° to 37° stair angle range).

Target Angle
34.2°
Angle Type
Acute Angle (Standard Stair Incline)
Complementary
55.8°
Supplementary
145.8°

How to Measure This Angle on an Image or Photo

International Residential Code (IRC) recommends stair angles between 30° and 37°. For a standard 7-inch rise and 10-inch run, the stringer angle is arctan(7/10) = 34.99 degrees. Verify existing stairs or architectural drawings using photo angle overlay.

Visual Diagram: 34.2° Angle Illustration
34.2°

Step-by-Step Measurement Procedure

  1. Upload your image: Drag and drop a photo or blueprint onto the Online Protractor canvas.
  2. Position Point B (Vertex): Drag the central vertex dot directly onto the corner or angle origin.
  3. Align Ray A (Baseline): Drag the left handle so ray A aligns perfectly with your reference line.
  4. Adjust Ray C (Angle Ray): Drag the right handle until ray C lies exactly along the sloped edge.
  5. Read Angle Output: The tool displays degrees, radians, complementary, and supplementary angles in real time.

Measure Your Angle Now

Upload any photo or image to measure angles with sub-degree accuracy in your browser.

Open Online Protractor Tool