Free Home Energy Calculators and Planning Tools
Generator sizing, battery runtime, solar payback, EV charging, outage food safety and a personal home power plan.
Every PowerProof Home tool is free, runs entirely in your browser, shows its working and never saves what you type. The tools recommend sizes and categories, never brands, so an affiliate commission can never shape a result.
Not sure where to start?
The Home Power Plan Builder asks six questions and builds a step-by-step plan that links to the right tools below.
Planning
Home Power Plan Builder
Six questions, one personalised step-by-step plan to keep your home powered, with the right tools and guides.
Generators
Home Generator Size Calculator
Add up running and starting watts for the appliances you need in an outage.
Transfer Switch Selector
Interlock kit, manual or automatic transfer switch: which usually fits your setup.
Batteries
Home Battery Backup Calculator
How long a home battery or power station runs your essentials, with or without solar.
Home Power Station Selector
List your devices to get the capacity, output and solar size you need.
Solar
Solar Payback Calculator
Payback years and long-term savings from your own quote, rate and sunshine.
Solar Panel Calculator
How many panels and what system size cover your yearly electricity use.
EV Charging
EV Charging Cost Calculator
Monthly cost of charging at home and the comparison with a gas car.
EV Charging Time Calculator
Hours to charge on Level 1 or Level 2 from your circuit and car.
Energy Savings
Electricity Cost Calculator
What any appliance costs to run per day, month and year.
Outage Prep
Power Outage Food Safety Timer
What USDA guidance says about your fridge and freezer after hours without power.
Power Outage Checklist
A printable checklist for before, during and after an outage.
How our calculators work
Each tool lists its assumptions, explains every step of the math, and links to the official sources behind its defaults, such as USDA for food safety and manufacturers’ wattage guides for appliances. Defaults are starting points: replace them with the numbers on your own appliance labels, utility bills and quotes for the most accurate result.
Have an idea for a tool? Tell us.