Energy & Electricity
EV charging, appliance running cost and generator sizing calculators for home energy.
EV Charging Cost Calculator (Home & Public)
Calculate the cost and time to charge an EV at home or public chargers from battery size, charger power and electricity rate.
Appliance Electricity Cost Calculator
Calculate the cost to run any appliance per day, week, month or year from its wattage, usage hours and electricity rate.
Generator Sizing Calculator (Running & Starting Watts)
Calculate the generator size you need from the running and starting watts of your appliances, with a recommended generator size.
What these tools are for
Every tool here multiplies a power figure by a time and a tariff, and every one of those three is less certain than it looks. Nameplate wattage is a maximum rather than a running figure; duty cycle is what actually decides consumption, which is why a 2 kW heater on a thermostat does not cost 2 kW an hour.
Charging and inverting both lose energy as heat. AC charging an EV commonly loses 10–20% between the wall and the battery, and cold weather makes it worse, so a calculation that ignores efficiency understates the bill by a noticeable margin.
Tariffs are the part a calculator cannot know. If you are on time-of-use pricing there is no single rate to enter, and the same appliance costs materially different amounts depending on when it runs.
Which one do I want?
- Costing an EV charge
- EV charging cost — set the efficiency, do not leave it at 100%.
- Costing an appliance
- Appliance electricity cost.
- Sizing a generator or battery
- Generator sizing or battery runtime — mind surge versus running watts.