Tools & calculators
Preparedness advice goes wrong when it is given in round numbers. A recommendation that suits a two-person apartment is wrong for a five-person house on a well, and no article can be specific enough to cover both.
These calculators do the arithmetic for your household instead. All of them show their working: the efficiency losses, the derating and the assumptions are printed next to the result, so you can disagree with any of them and see what changes. Results are free and none of them require an email address.
Run your own numbers
Solar Sizing Calculator
Array, battery bank and charge controller for the loads you actually run.
Water Storage Calculator
Gallons, containers, full weight and floor space for your household.
Power Station Runtime Calculator
How long a given battery will really run a refrigerator or freezer.
Inside the guide This calculator sits within its article, because its output only means anything alongside the assumptions the article sets out.
Generator Cord Size Calculator
Gauge and length for your load, before you buy the wrong cord.
Inside the guide This calculator sits within its article, because its output only means anything alongside the assumptions the article sets out.
Rainwater Collection Calculator
Gallons per inch of rainfall from your actual roof area.
Inside the guide This calculator sits within its article, because its output only means anything alongside the assumptions the article sets out.