Electrical & home energy
Free calculators for electricians, DIYers & homeowners
Free, accurate calculators for electricians, DIYers, and home-energy planning.
Voltage Drop Calculator
Check voltage drop % and size conductors for any run — copper or aluminum, single- or three-phase.
Open →Wire Size & Ampacity Calculator
Find the right wire gauge for a given current, distance, and voltage-drop limit.
Open →EV Charger Installation Cost
Estimate a Level 2 home EV charger install — hardware, labor, and panel work.
Open →Appliance Electricity Cost Calculator
See what any appliance costs to run per hour, day, month, and year at your rate.
Open →Heat Pump Cost Calculator
Estimate heat-pump install cost and running cost vs your current system.
Open →Why Wattwise
Every tool here does one job well, works without an account, and keeps your data in your browser. We publish the rules and sources behind each estimate so you can check our work.