All energy calculators

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

Bills

Electricity Bill Calculator

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

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Electricity Usage Calculator

Turn watts and hours into daily, monthly, and yearly kWh — and see what that usage costs.

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Electric Bill Breakdown

Estimate which appliances are behind your bill, and why it might be so high.

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Bill Splitter

Split an electricity bill fairly between roommates or tenants.

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Appliances

Appliance Cost Calculator

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

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Savings

Solar Payback Calculator

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

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Electricity Savings Planner

Pick the improvements you can make and see your potential monthly and yearly savings.

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LED Savings Calculator

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

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Appliance Upgrade ROI

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

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Compare Electricity Plans

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

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Advanced

Reverse Bill Calculator

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

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Time-of-Use Calculator

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

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Electrical

Watts to Amps Calculator

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

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Ohm's Law & Power Calculator

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

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Converters

Energy Unit Converter

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

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Appliance library

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