About BackupEngineer

Math shown, no sales pitch.

BackupEngineer is a free calculator and a set of guides that help homeowners figure out how much backup power they actually need, whether that's a portable generator, a standby generator, a portable power station, or a whole-home battery.

Review of the sizing math and the guides by a practicing power-electronics engineer (not a licensed PE) is pending. The engineer behind this site is not a licensed Professional Engineer (PE), and BackupEngineer does not provide engineering services, designs, or inspections for any home. Have a licensed electrician size and install your system.

The engineering background means we care about the details salespeople tend to skip: motor starting surge, fuel and altitude derating, inverter efficiency, 120 V vs. 240 V loads, and the safety rules that keep you and utility line workers alive.

What we promise

• The math is shown. Every result explains its formula, and the defaults cite their sources. You can change any number.
• Brand-neutral sizing. The calculator recommends sizes and capabilities, not brands.
• Honest about "you may need less." Most outages are hours, not days. We'll tell you when a smaller setup covers your essentials.
• Safety first. No backfeeding, a transfer switch or listed interlock installed by a licensed electrician, and carbon monoxide safety, every time.
• Clear disclosures. If we earn a commission on a link, the link says "(paid link)". See our affiliate disclosure.

What we are not

We're not your electrician, and this site is not electrical design or professional advice. We don't install equipment, sell generators, or take payment from brands to change our recommendations. Read the safety notes and disclaimer.

Contact

Corrections and questions are welcome: [email protected].