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Homelab · Tool · By Mohammed Almuhanna

Homelab Power & Electricity Cost Calculator

Devices

Tiered tariff (optional)

On a consumption-block tariff the lab's kWh land on top of the rest of the house, so they bill at whatever tier the household total already sits in. Price above is the below-threshold rate.

Embed this calculator on your site (free)

Free to use. The snippet is the calculator plus a one-line credit link, which is all I ask in return. It follows your visitor's light or dark setting automatically; add ?theme=light or ?theme=dark to the URL to pin it to your site.

Add your always-on devices, set your local kWh rate, and see total power consumption and electricity cost broken down by day, month, and year. A per-device breakdown shows where your bill is going.

How the cost math works

Electricity cost is watts times hours times your rate. Nothing else is going on. The calculator multiplies each device's watts by its hours per day and quantity, sums everything, converts to kilowatt-hours, and prices it at your rate. The monthly figure is the year divided by 12, so a short February does not wobble the number. A 74 W NAS-plus-mini-PC setup running 24/7 at $0.30/kWh comes to about $16 a month; the running-cost guide works that example by hand.

Do not bill a machine at its maximum draw, though. My workstation idles around 130 W and only climbs past 440 when I am gaming or hammering a build. Bill it at the peak around the clock and you triple the estimate. That is what the per-device idle and load fields are for: give each machine its real idle draw and the hours it actually works hard, and the number stops lying.

Sanity-check against real numbers

For a baseline: my rack (a five-bay Synology NAS around 50 W, an i9-9900K Proxmox server, and a UniFi PoE switch) averages about 210 W all in, roughly 150 kWh a month. I itemized the whole setup, priced at my actual tariff and at US, UK, and German rates, in what my homelab actually costs to run. If your total lands wildly off numbers like these, check the watts you entered before blaming the math.

Those are careful estimates, not meter readings; I do not own a plug-in meter yet. If you do, measure. A $20 meter beats any calculator, including mine.

Power calculator FAQ

How do I calculate a server's electricity cost?

Watts times hours per day, divided by 1000, gives kilowatt-hours per day; multiply by your rate for the cost. A 100 W server running 24/7 uses 2.4 kWh a day, about 876 kWh a year, which is $263 a year at $0.30/kWh. The calculator does this per device and adds it up.

How much power does a homelab use?

A Raspberry Pi idles in single digits, a mini PC sits around 10 to 20 W, a NAS with spinning drives lands near 30 to 60 W, and a tower server with a GPU pulls well over 100 W. The biggest single variable is whether a graphics card is involved.

Why enter idle and load watts separately?

Because most machines idle most of the time. A gaming PC that peaks at 440 W but idles at 130 W costs a fraction of what the peak suggests. Billing peak watts 24/7 is the most common way people overestimate a homelab's running cost.

Is a VPS cheaper than running a home server?

Power alone rarely decides it. A small always-on box costs a few dollars a month in electricity, so the real comparison is hardware cost, what your time is worth, and what the workload needs. I run both, and I wrote up when each one wins in home server vs VPS.