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Generator Sizing Calculator

Calculate the minimum generator wattage needed to power your home's essential loads, motors, and well pump during an outage. Use it before buying a standby or portable generator to avoid under-sizing.

Essential Loads (watts)

Motor Load (HP) (HP)

Well Pump (if any) (HP)

Startup Factor

Safety Margin

Fill in the required fields to see your result.

Electrical Home

Home Generator Size Calculator

Find the minimum wattage generator needed to power your essential home appliances during an outage. Accounts for motor startup surges that can trip or damage undersized generators.

Essential Appliances (watts)

Startup Factor (multiplier)

Fill in the required fields to see your result.

Key differences

	Generator Sizing Calculator	Home Generator Size Calculator
Category	Electrical Home	Electrical Home
Inputs required	5	2
Result	Minimum Generator Size (watts)	Generator Size Needed (watts)
What it does	Calculate the minimum generator wattage needed to power your home's essential loads, motors, and well pump during an outage. Use it before buying a standby or portable generator to avoid under-sizing.	Find the minimum wattage generator needed to power your essential home appliances during an outage. Accounts for motor startup surges that can trip or damage undersized generators.