About HowMuchWatts

HowMuchWatts provides free, easy-to-use calculators that help people understand the cost and savings of everyday energy decisions — from going solar to switching to a heat pump or an electric car.

Our approach

Every calculator shows the exact formula it uses in a “How it works” section, so you can check the maths yourself. We deliberately keep the models simple and conservative rather than optimistic, so you are never over-promised. The tools are free to use and supported by unobtrusive advertising.

Who’s behind HowMuchWatts

HowMuchWatts is an independent project run by a small team that is genuinely interested in home energy and the numbers behind it. We are not affiliated with any energy company, solar installer or manufacturer, and we do not accept payment to feature or favour any product — which is why our calculators stay deliberately neutral and conservative.

Every formula we use is published openly in the “How it works” section of each calculator, so you can check our maths rather than take it on trust. When we get something wrong or out of date, we fix it. Spotted an error or have a calculator you’d like us to build? We’d love to hear from you — contact us at hello@howmuchwatts.com.

Not financial advice

These tools give general estimates for educational purposes only. Real-world outcomes depend on many factors we cannot capture. Always verify figures and consult a qualified professional before making a purchase or financial decision.