Construction Math Calculator
Feet-inch math, stair and rafter triangles, roof pitch helpers, and unit conversion for carpenters and woodworkers who still think in fractions.
Calculator, Framing & Conversions
Feet-Inch Calculator
Right Triangle Solver
Hip & Valley Framer
Assumes standard 45° corner (Regular Roof).
Metric ↔ Imperial
How to Use Construction Math
Skip the phone calculator gymnastics when you need to add story poles, subtract reveal, or turn a pitch into a rafter length. Tabs cover general feet-inch math, triangles, roof helpers, and metric conversion.
Input formats
The parser understands most construction formats:
10' 6 1/2"(standard)10-6 1/2(dash notation)10 6 1/2(space separated)126.5(raw inches)
Framing tips
Use the triangle tab for stair stringers and common rafters when you know rise and run. The roof helpers give theoretical hip/valley length for a regular square plan (hip run = common run × √2). Always confirm birdsmouth and seat cuts against your framing square or layout software for irregular roofs.
FAQ
Should I enter finished or rough dimensions?
Match whatever you are calculating. Cut lists usually want rough stock sizes; reveal and overlay math should use finished openings.
How do I enter a measurement like 3/4 inch only?
Use 0 3/4 or 0.75. A bare 3/4 is also accepted as three-quarters of an inch.
Does the roof tab handle unequal pitches?
No — it assumes a regular 45° plan hip. For irregular or metal-building valleys, use StructLogic’s Hip & Valley calculator.
Can I use this on a phone in the field?
Yes. The layout is mobile-friendly; bookmark the page and keep Pro keys cleared if you want the free ad-supported version.