How we research

Every guide and calculator on this site is built from sources you can check. We do not run a test lab, so we never write that we tested a product. Here is what we do instead.

Our sources

• Government and public data: the U.S. Energy Information Administration (electricity rates), the Department of Energy, ENERGY STAR, the EPA, NOAA (climate and frost data) and the USDA (plant hardiness zones).
• Manufacturer specifications: spec sheets, manuals and safety labels.
• Owner reviews in bulk: when we compare products, we read reviews across many listings to find the problems owners report again and again, such as failures after a few months or claims that don't hold up.
• Codes and safety guidance: for electrical, gas and fuel topics we point to official safety guidance.

How our calculators work

Each calculator shows its formula and its assumptions under the result. Default values are typical figures, and every input can be changed to match your own device, home or bill. When public data has a date, such as electricity prices, we show it.

How we compare products

• We put specifications side by side in a table and calculate value figures, such as dollars per watt-hour.
• We say how many products and roughly how many reviews we looked at, and when.
• We say who each product suits, and who should skip it.

Keeping pages current

Each page shows the date it was last updated. We review pages regularly and update them when prices, data or products change.

Use of AI tools

We use AI tools to help gather sources and draft text. A person checks the facts and numbers, and is responsible for every page we publish.