Roof Pitch Calculator
Convert roof pitch to angle and area multiplier.
Roof pitch is expressed as the rise per 12 inches of horizontal run. The pitch multiplier used to size rafters and sheathing is √(1 + (rise/run)²). The angle in degrees is arctan(rise / run).
Angle
26.6
degrees
Pitch multiplier
1.118
6:12
Slope
50
%
Save this project
Sign in to save calculations to your dashboard.
Download your PDF report & project guide
Your results and inputs, a printable shopping list, a step-by-step guide and pro tips — in one PDF.
Planning a whole project?
Get every calculator, a full shopping list and a budget template for:
Recommended tools & materials
Handy picks for this project on Amazon.
Roofing Nailer
Speed up shingle installation
View on Amazon →
Synthetic Roof Underlayment
Lightweight, tear-resistant
View on Amazon →
Roofing Safety Harness Kit
Stay safe on steep pitches
View on Amazon →
Utility Knife with Hook Blades
Cut shingles cleanly
View on Amazon →
As an Amazon Associate, MaterialCalc earns from qualifying purchases.
How does the roof pitch calculator work?
Roof pitch is expressed as rise per 12 in of horizontal run. The pitch multiplier used to size rafters and sheathing is √(1 + (rise/run)²). Angle in degrees = arctan(rise / run).
Which guide explains this in more depth?
- Panel roofs waste differently from shingles: ribs, hips and valleys all change the number you order. Read the metal roofing calculator waste factor guide for the full worked example.
What else do people ask about this calculator?
What is a 6:12 roof pitch in degrees?
26.6° — the arctan of 6/12. A 4:12 is 18.4°, 8:12 is 33.7°, and 12:12 is 45°.
What is the pitch multiplier used for?
Multiply the flat (footprint) area by this factor to get the true sloped roof area for shingles and sheathing.
Which related calculators should I use next?
All calculators
Gear Up for Your Roofing Project
These practical tools and materials can help you measure, cut, and install roofing more efficiently.
Swanson Speed Square
Search on Amazon →
Milwaukee Utility Knife
Search on Amazon →
Keson 25-Foot Tape Measure
Search on Amazon →
Paid links: as an Amazon Associate, MaterialCalc earns from qualifying purchases.