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Homelab · Guide · By Mohammed Almuhanna · Updated
How Much Does It Cost to Run a Homelab?
A small always-on box costs a few dollars a month. A full server with drives and a GPU costs real money over a year. I run an old i9-9900K gaming PC as a 24/7 Proxmox server with a stack of containers, so I never turn it off, and that one box sets the floor on my power bill. It is just watts times hours times your rate, and "always on" means every hour of the year. Here is the math, real wattage numbers, and a worked example. If you want my actual itemized homelab bill, I broke it down on a separate page.
The short answer
Run a Raspberry Pi or a mini PC and nothing else, and you pay a few dollars a month. Those boxes idle at single-digit or low double-digit watts, so the yearly cost stays small. The bill climbs once you add a tower server, a stack of spinning hard drives, or a GPU that draws over 100 W under load. None of this is expensive per hour. Homelab gear just runs every hour of every day, so even a small draw turns into a real number across a year.
The math
Electricity is sold by the kilowatt-hour (kWh), which is 1,000 watts running for one hour. To get the cost of a device, multiply its watts by the hours it runs, divide by 1,000 to get kWh, then multiply by your rate.
watts × hours / 1000 × kWh rate
The "always on" part is what makes a homelab different from a desktop you switch off at night. A device left on 24/7 runs 730 hours in a month and 8,760 hours in a year. At those hours, even a few watts adds up. A box that idles at 10 W costs about 88 kWh a year, which is real money depending on where you live and what you pay.
Typical device wattages
These are idle ballparks from the kind of gear I run. Anything working hard pulls more than the figure below, so treat these as the floor, not the ceiling.
- Raspberry Pi: about 5 W
- Mini PC: about 10 to 20 W
- NAS (4-bay): about 30 to 40 W
- Tower server: about 60 to 100 W at idle, more under load
- Spinning hard drive: about 5 to 8 W each
- Network switch: about 10 W
- GPU: about 15 W idle, 150 W or more under load
Add up the gear you actually run, remember the drives and the switch, and you have your baseline draw.
A worked example
Say you run a mini PC at 15 W, a 4-bay NAS at 35 W, and 4 hard drives at 6 W each, all of it 24/7. We will use a sample rate of $0.30/kWh.
- Total power: 15 + 35 + (4 × 6) = 74 W
- Energy per month: 74 × 24 / 1000 × 365 / 12 = 54.02 kWh
- Energy per year: 74 × 24 / 1000 × 365 = 648.24 kWh
- Cost per month: 54.02 × $0.30 = $16.21
- Cost per year: 648.24 × $0.30 = $194.47
So a modest NAS-plus-mini-PC setup runs about $16 a month, or $194 a year, at that rate. This uses the same math the power calculator uses: 24/7 running, 365 days a year, and the month figured as the year divided by 12. Change the rate and the whole bill scales with it. At $0.15/kWh the same gear is about $8 a month.
How to cut the bill
- Pick low-power hardware. Mini PCs and ARM boards sip power. A Pi or an N100 mini PC does a lot of homelab work at under 20 W, where an old tower server might idle at 80 W doing the same job.
- Consolidate services. Running ten containers on one machine beats running them on three. Fewer powered-on boxes means a smaller baseline draw.
- Spin down idle drives or move to SSDs. A spinning drive you rarely touch still costs you 5 to 8 W around the clock. Spin it down when idle, or use SSDs, which draw less.
- Let machines sleep. If a box does not need to be on overnight, let it sleep or schedule it off. Hours not running are hours you do not pay for.
- Measure with a plug meter. A cheap inline power meter shows real idle draw, which is often different from the spec sheet. Measure before you guess.
- Watch the GPU. A GPU left in a machine still draws 15 W or more at idle, every hour, even when nothing is using it. If it is only for occasional transcoding or training, that idle draw adds up.
Let the calculator do it
You do not have to run this by hand. The homelab power and electricity cost calculator does it for any set of devices: add each one with its watts, hours per day, and quantity, set your kWh rate, and it shows daily, monthly, and yearly cost with a per-device breakdown. It runs in your browser and remembers nothing you do not enter.
Common questions
How much does it cost to run a homelab per month?
A Raspberry Pi or a single mini PC runs for a few dollars a month. A modest setup of a mini PC, a 4-bay NAS, and a few drives, around 74 W total at $0.30/kWh, comes to about $16 a month or $194 a year. Change your electricity rate and the whole bill scales with it.
How do I calculate the cost of running a device?
Multiply its watts by the hours it runs, divide by 1,000 to get kilowatt-hours, then multiply by your kWh rate. The formula is watts × hours / 1000 × kWh rate. A device left on 24/7 runs 730 hours in a month and 8,760 hours in a year.
Why does always-on gear cost so much over a year?
Homelab gear runs every hour of every day, so even a small draw adds up. A box that idles at just 10 W still uses about 88 kWh across a year. None of it is expensive per hour; the cost comes from the 8,760 hours a year it never switches off.
What is the easiest way to cut the bill?
Pick low-power hardware like a Pi or an N100 mini PC, consolidate services onto fewer machines, spin down idle drives or move to SSDs, and let boxes sleep when they are not needed. Measure real draw with a plug meter first, since spec sheets often overstate it.