About WattCost.org

WattCost.org is a free electricity cost calculator built to help households, renters, homeowners, EV drivers, and small businesses make quick, practical energy-cost estimates.

You can estimate appliance electricity costs, compare typical usage scenarios, and adjust the electricity rate to better match your country, state, province, or utility bill.

What WattCost is for

WattCost is designed for everyday planning: understanding what an appliance may cost to run, comparing energy use, estimating EV charging costs, and spotting where electricity usage may be higher than expected.

The goal is clarity, not complexity. We show the basic assumptions behind the calculation so users can change the inputs and understand how the estimate was produced.

How the calculators work

For appliance calculators, the basic formula is:

kWh used = watts ÷ 1,000 × hours used

Estimated cost = kWh used × electricity rate

Monthly estimates generally use a 30-day month, while yearly estimates generally use 365 days. EV calculations use the same energy-cost logic, with additional assumptions such as battery size, charging percentage, vehicle efficiency, or fuel comparison values where relevant.

Important limitations

All results are estimates. Actual electricity costs can vary based on appliance model, operating cycle, standby usage, local tariffs, taxes, delivery charges, time-of-use pricing, demand charges, climate, battery temperature, charging losses, and other real-world conditions.

WattCost does not provide electrical, financial, engineering, installation, tax, utility-billing, or energy-audit advice. Do not rely on this site as the only source for purchasing decisions, electrical work, EV charger installation, safety decisions, or significant financial commitments.

Electricity rates and data sources

WattCost includes pre-loaded electricity-rate data and typical appliance assumptions for convenience. These figures may come from public datasets, government or agency publications, utility-rate references, manufacturer-style typical values, and editorial estimates.

US electricity-rate references may include data from the EIA (U.S. Energy Information Administration). International references may include sources such as Eurostat, IEA-published data, public electricity statistics, and other reputable references. Rates are reviewed periodically but may not include every tax, fee, delivery component, time-of-use schedule, or local adjustment.

For the most accurate result, use the exact rate from your own electricity bill and the wattage shown on your appliance label or manufacturer documentation.

Privacy and calculations

No account or sign-up is required. Calculator inputs are processed in your browser, and WattCost does not intentionally collect appliance wattage, usage hours, EV charging values, or calculation results as personal records.

The site does use standard third-party services such as Google Analytics and Google AdSense. These services may use cookies, device identifiers, IP address, browser information, and similar technologies for analytics, advertising, fraud prevention, and ad measurement. Please review our Privacy Policy for details.

How we stay free

WattCost.org may be supported by advertising, including Google AdSense, and may include affiliate links. If you buy something through an affiliate link, we may earn a commission at no extra cost to you.

Advertising and affiliate relationships do not change calculator formulas, user-entered values, or calculation results.

Editorial independence

Calculator outputs are generated from the inputs and formulas shown on the site. We do not adjust results to favor any advertiser, affiliate, appliance brand, energy provider, or EV charging provider.

Corrections and updates

Electricity prices, appliance specifications, public charging prices, and emissions assumptions change over time. If you find an outdated rate, incorrect appliance wattage, broken link, or unclear explanation, please contact us with the source, date, country, state or province, and any relevant utility or appliance details.

We may update, annotate, or decline suggested corrections at our discretion, depending on source quality and relevance.

Legal notes

Use of this site is subject to our Terms of Use. Calculator results are informational estimates only and are provided without warranty.