Know exactly what your electricity costs.
Estimate your bill, find out what each appliance really costs to run, compare plans, and see how fast solar or LED upgrades pay back — all in one place, no sign-up required.
- No sign-up
- Free forever
- Any currency
- Official EIA data
Editable default — enter your own rate from your bill.
$102
≈ $3.35 per day
$1,224
600 kWh/mo × $0.17 /kWh
Every calculator you need
A growing suite of focused, easy-to-use energy tools.
Electricity Bill Calculator
Estimate your electricity bill from usage or appliance power — flat or tiered rates.
OpenAppliance Cost Calculator
See what any appliance costs to run per day, month, and year.
OpenBill Splitter
Split an electricity bill fairly between roommates or tenants.
OpenReverse Bill Calculator
Work backwards from a bill amount to estimate how many kWh you used.
OpenTime-of-Use Calculator
Calculate bills with peak, off-peak, and shoulder tariff periods.
OpenEnergy Unit Converter
Convert between watts, kilowatts, kWh, amps, and volts.
OpenSolar Payback Calculator
See how many years a solar system takes to pay for itself and its 25-year net savings.
OpenLED Savings Calculator
Compare old bulbs vs LEDs and see the yearly saving and payback time of switching.
OpenAppliance Upgrade ROI
Find out how long a more efficient appliance takes to pay back its purchase price.
OpenCompare Electricity Plans
Compare up to three tariffs side by side to see which plan is cheapest for your usage.
OpenWatts to Amps Calculator
Convert watts to amps (and back) for DC, single-phase, and three-phase AC circuits with power factor.
OpenOhm's Law & Power Calculator
Enter any two of volts, amps, watts, or ohms and instantly solve for the other two.
OpenPopular appliance costs
In-depth running-cost guides for the biggest energy users — with wattage ranges, usage scenarios, and money-saving tips for each.
Air Conditioner
5usage scenarios · running cost & saving tips
View guideKitchenRefrigerator
5usage scenarios · running cost & saving tips
View guideLaundryClothes Dryer
4usage scenarios · running cost & saving tips
View guideTransportEV Charger
4usage scenarios · running cost & saving tips
View guideElectronicsGaming PC / Console
5usage scenarios · running cost & saving tips
View guideHeatingElectric Water Heater
4usage scenarios · running cost & saving tips
View guideElectricity rates by US state
The US residential average is $0.19/kWh (Apr 2026). Compare your state and estimate a local bill.
Why Wattly
Instant & interactive
Slide, type, and watch results update live. No forms, no waiting, no account.
Works anywhere
Switch currencies and enter your own local rate — tiered and time-of-use supported.
Clear estimates
Transparent formulas you can trust — always cross-check with your official bill.