Roof Pitch Calculator

Roof pitch is the number that drives both safety and cost. The Roof Pitch Calculator converts a pitch expressed as x/12 (rise per 12" run) into the angle in degrees and the slope percent — and, most usefully, the roof-area multiplier (1 ÷ cos of the angle) that turns a flat plan footprint into the actual sloped surface you must cover.

Enter the pitch or the angle (they sync), optionally add plan area for the real roof square footage, and export the result for ordering underlayment and shingles.

• Two inputs: Pitch x/12 or angle° (auto-sync).
• Outputs: Angle, slope %, ratio.
• Area factor: 1/cos(angle) multiplier.
• Plan → roof area: Optional footprint input.
• Report & export: Copy or download as text, CSV or JSON.
• Learning guide: Pitch, degrees, factors.

1. Enter pitch x/12 (e.g., 6) or the angle in degrees — they stay in sync.
2. Read outputs: Angle, %, multiplier.
3. Optional: Enter plan area to get roof surface area.
4. Export. Copy or download.

Example 1 — 4/12. 18.43°, 33.3%, factor 1.054.

Example 2 — 6/12. 26.57°, 50%, factor 1.118.

Example 3 — 9/12. 36.87°, 75%, factor 1.25.

Example 4 — 12/12. 45°, 100%, factor 1.414.

Example 5 — Area. 1,000 ft² plan at 6/12 → 1,118 ft² roof.

• Degrees & % together: Match architect, roofer, supplier.
• True roof area: No under-ordering material.
• Sync inputs: Pitch or angle — your choice.
• Private: No account, nothing uploaded.