Construction Math Calculator
Feet-inch arithmetic, right-triangle solutions, roof pitch helpers, and inch/mm conversion for steel detailing and field layout.
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
This calculator is built for shop and field dimensions written in feet and inches. Use the tabs to switch between general math, triangle solutions, roof helpers, and metric conversion without rewriting every length by hand.
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)
Triangle and roof tabs
Enter any two known sides or a side and angle to solve the right triangle for layout marks. The roof helpers compute common, hip, and valley run/rise relationships for regular 45° plan hips (hip run = common run × √2). For irregular PEMB hips with unequal pitches, use the dedicated Hip & Valley tool instead.
FAQ
Why did my fraction fail to parse?
Use a space before the fraction (6 1/2) and ASCII quotes or omit the inch mark. Mixed numbers without a space (61/2) are read as sixty-one halves.
Can I chain several operations?
Yes on the math tab — treat it like a feet-inch aware calculator. Convert intermediate results to inches if you are mixing with decimal CAD values.
Is mm conversion exact?
Results use 25.4 mm per inch. Round to the fabrication tolerance on the drawing (often 1 mm or 1/16″) before releasing cut lists.
When should I use Hip & Valley Logic instead?
When two roof planes have different pitches or plan runs (typical lean-to valleys). This tab’s hip length assumes a regular 45° plan angle.