Knowledge Base · Running costs
How much does a home server really cost to run per year?
By Tiny · how I pick
A home server runs all day, every day, so its electricity cost is small but never stops. That cost depends almost entirely on how much power it draws while idle, not on how fast the chip is.
The math is simple, and once you've seen it, you'll know why every hardware guide on this site lists idle power.
Words you'll see in this guide
- Watt (W): a measure of how much power something uses at a given moment.
- Kilowatt-hour (kWh): 1,000 watts used for one hour. It's the unit on your electricity bill.
- Idle power: how much electricity a computer uses when it's on but not busy. For an always-on server, this number drives your power bill.
- Plug-in energy meter: a small device between the wall and a plug that shows how many watts something really uses.
The formula
Yearly cost = watts ÷ 1000 × 8,760 hours × your electricity rate
- 8,760 is the number of hours in a year.
- Your rate is on your utility bill, in dollars per kWh. The EIA expects the US average to be about $0.18/kWh in 2026. It runs from around 12 cents in the cheapest states to well over 30 cents in the most expensive, so check yours.
Worked example: a 10 W mini PC at $0.18/kWh is 10 ÷ 1000 × 8,760 × 0.18 ≈ $16 a year.
The table (at about $0.18/kWh)
| Always-on device | Typical idle draw | Cost per year |
|---|---|---|
| Raspberry Pi 5 | About 5 W | About $8 |
| Intel N100 mini PC | About 10 W | About $16 |
| Used tiny PC (i5-8500T) | About 15 W | About $24 |
| Small NAS (2 bays with drives) | About 25 W | About $39 |
| Old desktop reused as a server | About 60 W | About $95 |
| Tower with a graphics card | About 120 W | About $189 |
Why idle power matters more than speed
Your server spends almost all its time idle, waiting for something to do. It only hits full power for seconds at a time, during a video conversion, a backup, or an update. So the idle figure is what shapes your bill.
That's why a new N100 mini PC idling at 10 W can be a smarter buy than a "free" old desktop idling at 60 W. Over three years, the desktop costs about $235 more in electricity. That's a big chunk of what the mini PC would have cost.
How to measure your own box
- Plug an energy meter into the wall, and plug your server into the meter.
- Let the server sit idle for a few minutes after it starts.
- Read the watts.
That's your real idle number, which is often different from the spec sheet.
A basic meter is cheap, and it pays for itself the first time it talks you out of running a 60 W machine for a job a 10 W one could do.
Where to go next
- Want low-power boxes that still do real work? The best mini PC under $300 and media server guides list idle power for every pick.
- Weighing a new low-power box against a used one? See new vs used.
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