Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

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

Determine the right generator size (in kilowatts) to keep your home's essential appliances running during a power outage. Use it when planning an emergency generator purchase or sizing a transfer switch installation.

Essential Lighting (watts)

Refrigeration Load (watts)

Furnace Blower (watts)

Well Pump (watts)

Motor Starting Factor

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	5
Result	Minimum Generator Size (watts)	Recommended Generator Size (kW)
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.	Determine the right generator size (in kilowatts) to keep your home's essential appliances running during a power outage. Use it when planning an emergency generator purchase or sizing a transfer switch installation.