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Slope ratio (1:n) to degrees (and degrees to ratio)

Slope ratio (1:n) is common in ramps and accessibility specs, while most angle tools read degrees. This guide shows how to convert 1:n ↔ degrees, relate it to percent grade, and sanity-check on an image before exporting.

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Slope ratio (1:n) vs degrees (quick definitions)

A slope ratio 1:n means 1 unit of rise for n units of horizontal run. Example: 1:12 is 1 up for every 12 across.

Degrees describe the angle between the slope line and a true horizontal baseline.

Once you measure degrees, you can convert to a ratio (1:n), percent grade (%), or pitch (x/12) used in plans and specs.

Step-by-step

  1. 1
    Start from the format you have
    Note the value you’re given: 1:n ratio (like 1:12 or 1:20), degrees, or percent grade. Decide which direction you need for your report or check.
  2. 2
    Upload an image to verify (optional)
    If you have a ramp/roof/stairs photo, a plan, or a screenshot from a drawing, upload it so you can verify the slope visually before converting.
  3. 3
    Align a true horizontal baseline
    Rotate/flip and use the grid so a known horizontal reference is perfectly level. Degrees always reference true horizontal.
  4. 4
    Measure the slope in degrees
    Place the center at the slope start point. Keep the baseline on horizontal, rotate to match the slope edge, then read the degrees value.
  5. 5
    Convert, compare, and export
    Convert degrees ↔ 1:n ratio (and relate it to % grade if needed). Export PNG/PDF once the image and numbers agree.

Tips

  • Confirm the meaning of the ratio in your context: 1:n here is rise:run (vertical:horizontal).
  • If your result looks off, fix baseline alignment before re-measuring. Small tilts can change degrees noticeably.
  • Specs may define limits over a segment. An average slope in a photo might not match a max-slope requirement.
Alignment checklistPercent grade to degrees (and vice versa)Roof pitch to degrees (and degrees to pitch)

Related

Measure ramp slope angle
Measure ramp slope in degrees from a photo or plan, then compare to 1:n or percent requirements.
Measure stair stringer angle
Measure stair slope angle and relate it to drawings and conversion formats.
Measure roof pitch (slope) angle
Measure roof slope in degrees from a photo or plan, then convert to pitch formats.
PNG and PDF exports
Save a shareable image or a measurement report once the conversion is verified.
Slope Ratio (1:n) to Degrees (and Degrees to 1:n) | Smart Protractor