Trade calculators and resources for professionals who build things.
No subscription. No account. Works offline. Pay once.
Free Online Calculators
Professional-grade tools. No signup. No download required.
Voltage Drop Calculator
Calculate voltage drop for copper conductors. Single-phase, AWG 14–4/0.
Ohm's Law Calculator
Solve for voltage, current, resistance, or power from any two known values.
Stair Rise & Run
Total rise to riser count, actual riser height, and total run.
Roof Pitch Calculator
Convert between rise/run, X:12 pitch, and degrees.
Board Feet Calculator
Calculate board footage from dimensions or nominal lumber sizes.
Stud Count & Spacing
Wall length to stud count at 16", 24", or custom spacing.
Pipe Offset Calculator
Simple offsets at 22.5°, 30°, 45°, or 60° with travel and run.
Wire Size Reference
Amperage to minimum wire gauge for common loads.
Professional Apps — Coming Soon
Built for the jobsite. $9.99 once. No subscription. Ever.
Framing & Carpentry Calculator
$9.99 — one time
Stairs, rafters, board feet, compound miter, and more.
Electrician NEC Calculator
$9.99 — one time
NEC 2023 + 2026 wire sizing, conduit fill, voltage drop.
Pipefitter Calculator
$9.99 — one time
Pipe offsets, rolling offsets, parallel cutbacks, Victaulic tables.
Structural Span Calculator
$7.99 — one time
Joist spans, rafter spans, header sizing, deck beams.
Which NEC Edition Does Your State Enforce?
The most complete NEC adoption tracker online. Updated monthly.
Interactive state-by-state NEC adoption map