About WattWise

WattWise is a collection of free calculators for electricity, batteries, solar power and electronics. The goal is simple: give a correct answer quickly, and explain how it was worked out so you can trust it.

Who it is for

The electronics calculators cover the everyday work of designing and debugging circuits, from picking a resistor to writing constants for Verilog and VHDL. The power and energy tools apply the same engineering to everyday questions like "what does this heater cost to run?" or "will this power station last the night?" They are made for students, makers, engineers and homeowners alike.

How the calculators are made

• Every formula comes from standard engineering references and is shown on the page.
• Each tool is tested against hand-calculated examples before it is published.
• Assumptions (efficiency, losses, typical values) are stated next to the inputs and can be changed.
• All calculations run in your browser; nothing you enter is stored or sent to a server.

Found a mistake or want a new tool?

Please get in touch — corrections are fixed quickly and tool requests shape what gets built next.