Free Online Calculators

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.

Wire Size Reference

Amperage to minimum wire gauge for common loads.

Conduit Fill Calculator

NEC Chapter 9 conduit fill — EMT, Rigid, PVC with THHN/XHHW wire types.

Conduit Bend Calculator

Stub-up, offset, back-to-back, and saddle bend marks for EMT conduit.

EV Charging Calculator

Estimate charge time and cost for Level 1, Level 2, and DC fast charging.

Electricity Bill Estimator

Estimate monthly electricity cost from appliance wattage and usage hours.

Carpenters

Stair Rise & Run Calculator

Total rise to riser count, actual riser height, and total run with IRC compliance.

Carpenters

Roof Pitch Calculator

Convert between rise/run, X:12 pitch, and degrees.

Carpenters

Board Feet Calculator

Calculate board footage from dimensions or nominal lumber sizes.

Framers

Stud Count & Spacing

Wall length to stud count at 12", 16", 24", or custom spacing.

Pipefitters

Pipe Offset Calculator

Simple and rolling offsets with SVG diagram.

Drainage Slope Calculator

Calculate drop, slope percentage, and pipe elevation for drainage runs.

Pipe Sizing Calculator

Size water supply pipes based on fixture units and flow rate.

Water Pressure Drop Calculator

Estimate friction loss in water pipes using Hazen-Williams formula.

Gas Line Sizing Calculator

Size natural gas and propane piping by BTU load and pipe length.

Career & Business

Pay calculators, apprentice tools, and business math for working tradespeople.

Construction Overtime Calculator

Federal, California daily, and prevailing wage overtime with double-time support.

Union Take-Home Pay Calculator

Gross to net with FICA, taxes, union dues, working dues, and pension.

Apprentice Wage Progression

IBEW, UA, and UBC apprentice pay at each period based on journeyman rate.