Backup Generator Calculator

Size a generator for hybrid solar or emergency backup.

Continuous Load (Watts) Running watts of essential loads

Largest Motor Load (Watts) Well pump, AC compressor, etc.

Motor Starting Factor

Generator Purpose

Battery Bank Size (kWh) - If Hybrid

Size	Running	Starting	Use Case
3,500W	3,000W	4,000W	Essential circuits
5,000W	5,000W	6,250W	Small home
7,500W	7,500W	9,500W	Medium home
10,000W	10,000W	12,500W	Large home
15,000W	15,000W	18,750W	Whole house

Generator Sizing