# BackupPowerCalc

> Surge-accurate backup power sizing. We size generators and batteries by the
> realistic peak: total running watts plus the single largest startup surge.

## Method
- peak = sum(running watts) + single largest startup surge delta
- Apply 20% safety margin, round up to nearest 500W class.
- Only ONE motor surges at the peak instant (good practice staggers starts);
  summing every surge oversizes the generator.

## Surge multipliers
- Resistive/electronic: 1.0x (no surge)
- Light motor: 2.0x
- Induction motor: 2.5x
- Compressor/heavy motor: 3.0x

## Key pages
- Load sizer: https://backuppowercalc.com/calculators/load-sizer.html
- Methodology: https://backuppowercalc.com/guides/methodology.html
- Running vs starting watts: https://backuppowercalc.com/guides/running-vs-starting-watts.html