The Electrician's On-the-Van Calculation Companion

Ohm's law, voltage drop over a cable run, and labor plus materials quotes: type them the way you would sketch them on a job sheet and read the answers next to each line.

Try the Web App Download for Mac

Built for electricians

Ohm's Law with Named Values

Define `voltage = 240` and `resistance = 12`, then reference them in `current = voltage / resistance` and `voltage * current`. Change any input and every dependent line updates.

Voltage Drop over a Cable Run

Estimate drop across a run with a plain expression: `2 * current * distance meters * ohms per meter`. Rename the lines and every substitution stays visible.

Trade Unit Conversions

Switch between metric and imperial without a lookup table: type `12 mm to inches`, `50 feet to meters`, or `40 celsius to fahrenheit` for a panel rating check.

One Tab Per Job

With Lifetime, keep every quote and load calculation on its own tab. Rename tabs by job address so you can flip back to yesterday's panel numbers without losing the current bench-top notes.

See It in Action

Ohm's law

voltage = 240
resistance = 12
current = voltage / resistance
voltage * current

Voltage drop

current = 20
distance meters = 30
ohms per meter = 0.0068
2 * current * distance meters * ohms per meter

Job quote

labor hours = 3
hourly rate = 75 USD
materials = 120 USD
subtotal = labor hours * hourly rate + materials
subtotal + 15%

Start calculating smarter, electricians.

Notes Calculator is free to start, runs in your browser, and works on every desktop. Upgrade later for sync and unlimited tabs.

Open the free web app See pricing

Free forever plan · No credit card · Cross-platform