All energy calculators

A complete index of every tool in the Wattly energy cost toolkit, grouped by what you're trying to do.

Bills

Estimate your electricity bill from usage or appliance power — flat or tiered rates.

Split an electricity bill fairly between roommates or tenants.

See what any appliance costs to run per day, month, and year.

See how many years a solar system takes to pay for itself and its 25-year net savings.

Compare old bulbs vs LEDs and see the yearly saving and payback time of switching.

Find out how long a more efficient appliance takes to pay back its purchase price.

Compare up to three tariffs side by side to see which plan is cheapest for your usage.

Work backwards from a bill amount to estimate how many kWh you used.

Calculate bills with peak, off-peak, and shoulder tariff periods.

Convert watts to amps (and back) for DC, single-phase, and three-phase AC circuits with power factor.

Enter any two of volts, amps, watts, or ohms and instantly solve for the other two.

Convert between watts, kilowatts, kWh, amps, and volts.

20 appliances with typical power ratings and running-cost estimates.