Together with Sheet B, this answers the only two questions that matter before you spend money on backup power: how much energy does my house actually need per day — and what size unit covers that number? Do the worksheet before you shop. The number decides — not the ad.
Running watts = what a device uses while on. Surge watts = the burst a motor needs to start (fridges, sump pumps — often 2–3× running). Running watts × hours per day = daily watt-hours per device. Add the column: that's your daily number. Then size with honest margin — plan on roughly 85–90% of a battery's rated capacity being usable.
| Device | Running W | Hours/day | Daily Wh |
|---|---|---|---|
| Phone charging × 2 | 10 | 3 | 60 |
| Wi-Fi router + modem | 15 | 12 | 180 |
| LED lamp × 2 | 16 | 5 | 80 |
| CPAP (no humidifier) | 40 | 8 | 320 |
| Box fan | 60 | 6 | 360 |
| Total | 1,000 Wh |
1,000 Wh ÷ 0.85 = ~1,180 Wh → shop the 1–2 kWh class (Sheet B maps every class).
The full pack includes the blank 12-device audit grid, the sizing sheet, and the online calculator that does the math for you.