About Ohm Calculator
Ohm Calculator is a free, fast, mobile-first tool for everyday electrical math. It helps homeowners, students, electricians, makers, and anyone with a utility bill convert between the core units of electrical power — amps, volts, watts, and kilowatts — and estimate what an appliance actually costs to run.
What you can do here
- Power Converter (Ohm's Law): enter any two of amps, volts, watts, or kilowatts and the remaining values are calculated instantly, based on the relationship Watts = Amps × Volts.
- Energy Cost Calculator: enter an appliance's wattage, how many hours a day it runs, and your electricity rate to see the cost per day, month, and year.
- Shareable results: your inputs are saved to the page URL as you type, so you can bookmark or share a calculation with a single tap using the "Copy Results" button.
Why we built it
Most electrical calculators are slow, cluttered, or buried in ads that get in the way of the tool itself. We wanted something that loads instantly, works well on a phone while you're standing at a breaker panel or reading an appliance label, and gives an answer the moment you start typing — no "Calculate" button required.
A note on accuracy
The calculations here are based on standard electrical formulas and assume ideal, purely resistive conditions. Real-world factors — power factor, voltage drop, wiring losses, motor start-up surges, and local electrical code — can change the figures. Our results are intended for quick estimates and learning, not as a substitute for professional advice. For installation, safety, or billing decisions, always consult a licensed electrician and your utility provider.
Contact
Questions, corrections, or suggestions are welcome at hello@ohmcalculator.com.