Measure an average that includes real jobs
Network storage can alternate between idle, drive access, backups, media processing, updates and sleep. A 30 W display reading at one moment does not prove a 30 W monthly average. Use cumulative kWh over at least 24 hours, and preferably a normal week that includes scheduled tasks.
Divide measured kWh by hours and multiply by 1,000 if you want the period-average watts. For example, 5.04 kWh over seven days equals 30 W average: 5.04 ÷ 168 × 1,000. You can calculate cost directly from the 5.04 kWh without converting back to watts.
Project the measured average carefully
At 30 W average, monthly energy is 0.03 kW × 24 hours × 30 days = 21.6 kWh. At $0.18/kWh, the cost is $3.888, rounded to $3.89. A 31-day month would use 22.32 kWh under the same average, so state the period used.
The estimate covers only equipment included behind the meter. A router, network switch, external backup drive or uninterruptible power supply may draw additional energy. Measure the whole stack or keep each device in a separate row.
| Average input | 30-day energy | Cost at $0.18/kWh | Annualized energy |
|---|---|---|---|
| 15 W | 10.8 kWh | $1.94 | 131.4 kWh |
| 30 W | 21.6 kWh | $3.89 | 262.8 kWh |
| 60 W | 43.2 kWh | $7.78 | 525.6 kWh |
Repeat the weekly measurement after changing drive-sleep or backup settings. A shorter idle reading cannot show whether a later indexing or backup job simply moved the energy to another hour. Compare complete work cycles and preserve the same meter boundary.
Test changes without risking the data
Drive sleep, scheduled shutdown and reduced background activity may lower consumption, but they can also affect availability, backups and drive behavior. Read the hardware and storage-system documentation before changing settings, and maintain verified backups. Energy saving is not worth losing irreplaceable data.
Compare equal seven-day windows when possible. Record backup schedules, users, media jobs and firmware changes so that a low-activity holiday week is not presented as normal operation.
Use cost to support a wider ownership decision
Electricity is only one part of owning a NAS. Storage capacity, redundancy strategy, replacement drives, backup media and maintenance can outweigh the power bill. Do not interpret a low monthly electricity result as proof that a configuration is reliable or economical overall.
Keep the model, drive count, meter boundary, dates, measured kWh and rate beside the estimate. This makes the page useful again when you add drives, change tariffs or move scheduled jobs to different hours.
Choose your next step
Continue with the question that matches your next decision:
Sources & further reading
Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.