Electrical
Electrical maths that gets the details right.
Power factor, three-phase, continuous loads, and real ampacity tables. Most calculators online skip all four, which is exactly where the answers go wrong.
Watts, amps, and volts converter
Leave one field blank and it solves for that one. Handles three-phase and power factor.
1.0 for resistive loads (heaters, incandescent). Motors typically 0.8–0.9.
Every one of these runs live as you type — no submit button, no page reload. Leave a field blank and it simply doesn't contribute.
A note on what these are for. They're sizing and estimating tools, and they're deliberately conservative. They cannot know your termination temperature ratings, how many conductors share a raceway, the ambient temperature, or what your local amendments say — and all four change the answer. Use them to plan and to sanity-check, then have a licensed electrician confirm anything you're going to build or energise.
Where a figure comes from a code section, the section is named so you can look it up rather than take our word for it.
Every calculator
Watts, amps, volts
Leave one field blank and it solves for that one. Handles three-phase and power factor.
Read thisWire size
Minimum conductor and breaker, with the 125% continuous-load rule applied.
Read thisVoltage drop
The thing that actually sets wire size on long runs.
Read thisRunning cost
What that appliance actually costs you per year.
Read thisQuestions
Are these safe to build from?
They're planning and checking tools, and they're deliberately conservative. They can't account for termination ratings, conduit fill, ambient temperature, or local amendments — all of which change the answer. Have a licensed electrician confirm anything you intend to build or energise.
Which code edition is this based on?
The ampacity figures follow the 75°C column of NEC 310.16 and the standard overcurrent sizes in 240.6(A). Adoption lags by state and local amendments vary, so confirm against the edition your jurisdiction has actually adopted.
Do you store what I enter?
No. Every calculation runs in your browser. Nothing is sent anywhere and nothing is saved.