About WattMaths

Why I built it

When I looked at the energy calculators already out there, I kept running into the same three problems.

1. The maths was hidden. You got a number, but no way to check it.
2. The numbers were old. Rates and rebates change every year, and many calculators never caught up.
3. Nobody said where the figures came from.

So I built the calculators I wanted to use. Each one names its sources and shows how the result was worked out.

Who I am

I'm a full-stack and AI engineer with 6+ years building production web apps. I also founded Finance Flow, a finance platform for freelancers and small businesses, so tools that handle money are my everyday work.

How the numbers are checked

• We prefer the official source. When we cannot read a number on the official page, we use a dated third-party page. When no source gives it at all, we work out our own estimate and say what it is based on. Any other figure we have not yet checked against the official page carries the “Not yet checked” label.
• A label says how far a figure has been checked:Official sourceDated third-party sourceEstimateNot yet checked
• We review every data file at least every 90 days, and each page shows when.

See every source and where we use it·See how we calculate

What WattMaths is not

• Not financial advice. The calculators give you an estimate to decide with. Your own bill and quote come first.
• Not paid placement. No retailer or installer pays to appear, and no result is pushed toward a sale. WattMaths is free. We plan to pay for it with ads.
• Not a sales funnel. We never ask for your phone number.

Found a wrong number?

Rates change fast. If a figure looks wrong, email me at hello@wattmaths.com with the page and what you found. I fix confirmed errors and update the review date.