ClutchCalcs

Construction

Generator Sizing

Pick the appliances you want to run during a power outage. We total running watts + the largest motor surge, recommend the generator size.

Pick what you want to run

FAQ

Running vs surge watts? +
Running watts is steady-state. Surge (starting) watts is the spike when a motor kicks on — refrigerators, AC, well pumps surge 2-3× their running watts for 1-2 seconds. Generator must handle BOTH.
Portable vs standby? +
Portable (3-12 kW): plug in extension cords, no install, $400-$1500. Standby (10-30 kW): auto-start whole-home, professionally installed, $5000-$15000 including transfer switch and concrete pad.
Fuel cost? +
Portable gas: ~$30-50/day at 50% load. Standby propane: ~$50-100/day. Standby natural gas: ~$30-60/day. Run-time depends on tank size.