Slope / Gradient Calculator

Slope shows up everywhere — ramps, roof pitches, driveways, and especially drainage, where the wrong fall causes standing water. The Slope / Gradient Calculator takes a rise and a run and returns the three ways slope is expressed: the ratio (1:x), the percent grade, and the angle in degrees.

Pick your unit, enter rise and run, and read all three together. Use it to check ADA ramp limits, set a drainage fall, or verify a roof pitch — and export the result for your plans.

• Three outputs: Ratio 1:x, percent grade, angle°.
• Unit toggle: ft, in, m, cm (ratio is unitless).
• Rise-per-12 helper: Read ramp/drainage fall directly.
• Live: Updates as you type.
• Report & export: Copy or download as text, CSV or JSON.
• Learning guide: Ratios, %, angles explained.

1. Pick unit. ft, in, m or cm (rise & run same unit).
2. Enter rise. Vertical change.
3. Enter run. Horizontal distance.
4. Read outputs. Ratio, %, angle, rise-per-12.
5. Export. Copy or download.

Example 1 — ADA ramp. 1 rise : 12 run → 8.33%, 4.76°, 1" per foot.

Example 2 — Drainage. 0.25 rise : 12 run → 2.08%, 1:48 (1/4" per foot).

Example 3 — Driveway. 2 rise : 20 run → 10%, 5.71°.

Example 4 — Roof. 6 rise : 12 run → 26.57°, 50%, 1:2.

Example 5 — Gentle grade. 1 rise : 50 run → 2%, 1:50.

• All three at once: Ratio, %, angle — no separate tools.
• Ramp-ready: Check ADA 1:12 instantly.
• Drainage correct: Set the right fall, avoid puddles.
• Private: No account, nothing uploaded.