Free energy calculators that show what you pay
WattlyCalc is a growing set of fast, focused energy calculators that run entirely in your browser. What an appliance costs to run, what it costs to charge an EV, whether electric beats gas, when solar pays for itself. One job per tool, no signup, and nothing you type ever leaves your device.
No signup
Runs in your browser
Free forever
Updated for 2026
Tools
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Electricity Cost Calculator
What any appliance costs to run per hour, day, month, and year, at your rate.
Live
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EV Charging Cost Calculator
Cost to charge an electric car at home or in public, per charge and per mile.
Live
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EV vs Gas Calculator
Compare the yearly fuel cost of an electric car against a gas car.
Live
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Solar Panel Calculator
How long a home solar system takes to pay for itself in your state.
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Heat Pump Calculator
Yearly savings of a heat pump versus a gas furnace, with credits.
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Home Battery Calculator
Whether a home battery pays back through time of use rate savings.
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Why WattlyCalc
Built for one job
Each tool answers a single question well, so you get to the answer fast and the page stays easy to read.
Private by design
Every calculation happens in your browser. Your numbers are never sent to a server or stored anywhere.
Your real rate
Energy cost depends on the price you pay per kilowatt hour. Every tool lets you set your own rate, with the current national average preloaded.
Free, no account
No login, no paywall, no email required. Open a tool and start.