Feet-Inch Calculator for Steel Detailing
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
Steel Shop Construction Math
Detailers and estimators still need feet-inch arithmetic when a drawing calls out stick-out, seat depth, or a brace from node to node. This calculator is for the steel shop and field trailer: parse mixed feet-inch strings, solve right triangles for bracing and stair geometry, convert millimetre exports from BIM, and get a quick regular-plan hip length when you are sanity-checking a pitched canopy — without opening CAD for every scratch calculation.
Results display in feet and inches (nearest sixteenth) plus a decimal-inch readout so you can paste into a spreadsheet that expects inches or hand-mark a tape that expects fractional inches.
When to use each tab
- Math — Add grip plies, subtract weld access clearances, multiply a member length by piece count, or divide a run for equal hole spacing along a plate.
- Triangle — Solve brace length from rise and run, or back-calculate rise when a diagonal is fixed by the architectural section.
- Roof — Approximate common and hip lengths for a regular 45° plan hip (hip plan run = common run × √2). Use this only as a check — not for unequal PEMB valleys.
- Convert — Translate millimetre shop drawings or European mill certs into imperial fabrication units (25.4 mm per inch).
Parsing shop callouts
Enter lengths the way they appear on erection drawings and cut lists:
10' 6 1/2"— feet, inches, and fraction with marks10-6 1/2— dash form common on North American fab tickets126.5— decimal inches from CAD or CNC reports
Always leave a space before a fraction (6 1/2). Mixed numbers without a space (61/2) are read as sixty-one halves and will throw your takeoff off by feet.
Detailing vs dedicated roof tools
The roof tab assumes equal pitches and a square plan angle. Lean-to valleys, unequal main/lean-to pitches, and PEMB trim plate break angles belong in Hip & Valley Logic. Stair riser/tread code checks belong in the Stair Calculator with IBC / OSHA / IRC toggles — use the triangle tab here only for raw geometry, not code compliance.
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?
Whenever two roof planes have different pitches or plan runs (typical lean-to valleys and PEMB trim). This tab’s hip length assumes a regular 45° plan angle.
Is this a substitute for connection design software?
No. Use it for layout arithmetic and takeoff checks. Bolt capacity, weld size, and member design still follow your detailer standards and the engineer of record.
Where this fits in the workflow
- Stair Stringer & Headroom Calculator Stringer geometry with code checks rather than raw triangles.
- Roof Pitch & Slope Converter Convert a solved rise and run into a pitch callout.
- AISC Steel Shape Database Look up the member dimensions you are adding and subtracting.
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