Methodology: how we calculate running costs

Electricity prices

State prices come from the U.S. Energy Information Administration's Electric Power Monthly, Table 5.6.A: the average price of electricity to residential customers, in cents per kWh. The current figures are for July 2026 (released September 24, 2026). This average equals residential revenue divided by residential sales, so it blends all utilities, plans and fixed charges in a state. We update after each monthly EIA release.

Appliance energy use

• Watt-based estimates: kWh = watts × hours ÷ 1,000. This is an upper bound for appliances that cycle on and off.
• Rated yearly energy: where ENERGY STAR publishes a rated annual kWh (for example, dehumidifiers), we use that figure as reported. It comes from the Department of Energy test procedure and reflects standard assumptions, not your home.

Cost

cost = kWh × price per kWh

We round money to the nearest cent (or dollar for yearly figures). Percentage changes are our own calculation from the source values.

Our own analysis

When a page reports statistics such as medians or counts, we computed them from the full public dataset on the retrieval date stated on that page. We keep the raw download and the calculation so results can be reproduced. Where records look internally inconsistent, we flag them rather than silently delete them.

Use of AI

We use AI tools to help research, structure and draft pages. AI output is never published without checking every number and claim against the cited source. We don't use AI to invent testing, quotes, experts or experiences.

Limitations

All figures are estimates. Your utility's tariff, time-of-use pricing, taxes, how you use the appliance and the weather will change your real cost. Your bill is the final word.