Contact

Email [email protected]. One person reads it, so give it a day or two.

Found a number that looks wrong?

Please say so. These tools use trade conventions and rules of thumb, and some of them deserve challenging. Tell us which calculator, what you entered and what you expected, and we will check the maths and publish a correction if it is wrong.

Want a calculator that is not here?

Say what you were trying to work out. Requests that keep coming up get built.

Privacy, data, or the site itself

See Privacy first — the short version is that this site sets no cookies and your numbers never leave your browser. Anything that page does not answer, email us.

What we cannot do

We cannot sign off on your installation, specify your wiring, or act as your electrician. These tools give planning estimates. Anything involving circuits, load or structure needs a qualified person who has seen the actual job.