Homelab Power & Cost Calculator

Worked examples

These are this calculator’s own outputs, computed with the same formula the tool runs in your browser — so you can see a real answer without touching a single input.

The tool’s own default state — what every visitor sees on page load with no URL parameters: a Proxmox mini PC plus a 4-bay HDD NAS, at the default US-average rate

• Inputs: Rate = $0.184/kWh (the default); cloud = blank. Device 1 “Proxmox Mini PC”: idle 20 W, load 45 W, 4 hrs/day at load. Device 2 “4-Bay NAS”: idle 28 W, load 55 W, 4 hrs/day at load.
• Result: Combined load draw 100 W · Annual usage 496 kWh · Monthly cost $8 · Annual cost $91 · 3-year operating cost $274. (No vs-cloud panel: cloud field is empty.)

GPU workstation AI node plus a 10GbE switch, both loaded straight from the tool’s built-in presets, and compared against an $80/month cloud GPU/VPS bill — this exercises the vs-cloud output path

• Inputs: Rate = $0.184/kWh (the default); cloud = $80/mo. Device 1 = preset “GPU workstation (RTX 5080)”: idle 80 W, load 450 W, 5 hrs/day. Device 2 = preset “MikroTik CRS305 switch”: idle 8 W, load 10 W, 24 hrs/day.
• Result: Combined load draw 460 W · Annual usage 1,464 kWh · Monthly cost $22 · Annual cost $269 · 3-year operating cost $808 · vs cloud ($80/mo equivalent): +$2,072 — “Homelab saves $2,072 over 3 years vs $2,880 in cloud spend.”

A gaming PC left on all day, then the same PC shut down after playing — the “Gaming PC (RTX 5080 class)” preset, then its idle set to 0

• Inputs: Rate = $0.184/kWh (the default); cloud = blank. One device from the preset: idle 85 W, load 420 W, 4 hrs/day at load. Second run: idle changed to 0 W.
• Result, left on: Combined load draw 420 W · Annual usage 1,234 kWh · Monthly cost $19 · Annual cost $227 · 3-year operating cost $681.
• Result, shut down after playing: Combined load draw 420 W · Annual usage 613 kWh · Monthly cost $9 · Annual cost $113 · 3-year operating cost $338.

How much electricity does a gaming PC use?

Per hour, far more goes into gaming than into sitting at the desktop. Take the RTX 5080 box in the worked example above: a 420 W load budget works out to 0.42 kWh per hour of gaming, about 8 cents at the US-average $0.184/kWh. Four hours a day is about $113 a year.

The surprise is the rest of the day. Left on at 85 W idle for the other 20 hours, the same PC uses about as much energy as it does gaming and adds about $114 a year. Shutting it down after play halves the bill.

To run your own numbers, pick the “Gaming PC (RTX 5080 class)” preset, which loads those three inputs, then change them to yours. The 420 W is an illustrative whole-system input, not a measured maximum: the card in that box drew 266 to 340 W in games at stock. Set idle to 0 for a PC you shut down, or to its measured sleep draw. The formula is the one below, kWh per day = (idle W x idle hours + load W x load hours) / 1000.

How to use this calculator

Add each device in your homelab — mini PC, NAS, switches, GPU node, whatever is running 24/7 or close to it. For each device you need three numbers:

If you arrive from the NAS & RAID Capacity Calculator, the page keeps your drive and RAID choices, optional user-entered purchase price, and a return link. The NAS wattage row is only the existing 4-bay starting estimate; capacity does not imply watts. When a purchase price is present, a separate card combines that one upfront NAS amount with three years of electricity for all listed devices; other devices’ purchase prices are excluded.

The budget NAS build guide can also open this tool with Notebookcheck’s dated AOOSTAR WTR Pro 5825U test-unit measurements. The page shows the source, listed one-SSD test configuration and workload. The review does not identify hard drives in that configuration. Four load hours per day is only an editable example; measure your own drives and duty cycle before treating the output as a personal estimate.

• Idle watts — what the device draws when powered on but not under active load
• Load watts — representative average whole-system wall draw during the active hours you enter. A brief startup or workload peak is not the average for all those hours.
• Hours per day at load — how many hours per day the device is actually under that higher load; the rest of the 24 hours is assumed idle

Hit any field and the results update instantly. The shareable URL captures your full configuration — bookmark it, share it, or come back later.

Getting accurate watt numbers

The presets are good starting points. They use representative figures from manufacturer specs and community measurements. But “representative” is not the same as “your unit specifically.”

Best method: measure at the wall. An energy meter such as the P3 P4400 ES can measure the device at its outlet. Let the system settle before observing idle draw. For a changing workload, record energy over a representative interval and calculate average power; a single benchmark or startup peak is not the average consumption for every active hour. Match the measured workload to how you actually use the device.

If you cannot measure: use a whole-system wall-power measurement for the same configuration. CPU TDP and CPU package telemetry cover a component, not the PC at its outlet. Intel defines processor base power as a processor thermal-design target. Memory, drives, fans, the GPU and power-supply losses also affect the wall reading. Do not enter the CPU’s TDP as this calculator’s device load watts.

Match the source’s workload, installed drives and power settings to your setup. A review’s idle result is not a load result, and a maximum stress-test result is not necessarily the average during your work. When the load varies, measure energy over a representative period and divide by elapsed hours to get average watts, as the US Department of Energy’s measurement guidance explains. Keep peak-load measurements separately for UPS sizing.

TechFuel HQ dataset. The site’s GPU dataset page at /data/ publishes measured power draw for the RTX 5080 and other hardware I’ve tested directly. Those figures are from real measurements, not spec sheets.

CPU package watts are not wall watts

A CPU monitor’s package power reading covers a processor package. It does not cover the entire computer. The Linux kernel’s RAPL documentation describes package power as its own monitored zone, with core and uncore subzones. Separate loads in the PC remain outside that reading, including the graphics card, drives, fans and some power-conversion losses.

Use package power to compare CPU behavior under the same workload. For this calculator’s PC idle and load fields, use whole-system input power from a plug-in meter at the wall. If only a package sensor is available, do not paste it in as though it were the PC total.

Measure the completed machine, or use a clearly labelled whole-system estimate until you can. The P3 P4400 product page is the source for the wall meter already used in the method above; the kernel powercap documentation defines the narrower package zone.

What “idle” means here. Idle means powered on, OS loaded, services running, but not under active workload. For Proxmox this means VMs are running but not doing much. For a NAS this means drives have spun up and the array is mounted but not actively transferring. True power-off is not useful here — you want 24/7 operating cost, which is exactly what always-on idle draw adds up to over a year.

Understanding the outputs

Combined load draw (W) — the sum of entered load watts. Some presets and source-linked measurements describe a workload average rather than each device’s true maximum. Use measured or manufacturer-supported worst-case simultaneous wall draw and an electrician’s circuit guidance for capacity planning; the default total is not a UPS or circuit rating.

Annual kWh — total energy consumed per year across all devices. This is the number that maps directly to your utility bill. Formula: for each device, ((idle_W × (24 − hrs)) + (load_W × hrs)) × 365 / 1000.

Monthly cost / Annual cost — annual kWh times your rate, divided by 12 for the monthly figure. This is what the homelab adds to your electricity bill.

3-Year operating cost - three years of electricity only. A separate combined card appears for a NAS plan with an entered purchase price; it is not a complete ownership-cost forecast for additional devices.

vs. Cloud delta — if you entered a cloud monthly equivalent (a VPS or hosted server you’d be paying instead), this shows the 3-year difference. Positive delta means homelab electricity is cheaper than cloud over three years. Negative means cloud wins on operating cost — though it usually ignores what you get: root access, no data egress fees, and the ability to run AI inference locally without paying per-token.

Real-world example configurations

These are illustrative input scenarios. Enter values measured for your own whole system when available; presets are starting estimates.

Starter stack: Mini PC + 4-bay NAS

The most common homelab entry point. A Beelink SEi12/N150-class mini PC running Proxmox plus a Synology or TrueNAS Scale unit on a 4-bay chassis.

At the default $0.184/kWh: the calculator returns 521 kWh/year — $8/month, $96/year, $288 over 3 years, at a 110W combined load draw. This is the modeled electricity expense for these inputs, before acquisition, maintenance, network and replacement costs.

Three-node Proxmox cluster

Three identical mini PCs forming a Proxmox VE quorum cluster. Typical setup for high-availability VMs.

At the default $0.184/kWh: the calculator returns 879 kWh/year — $13/month, $162/year, $485 over 3 years, at a 179W combined load draw. For a HA cluster running a dozen VMs plus shared storage, that is remarkably cheap. The 10GbE switch adds maybe $1/month.

GPU workstation AI node

An RTX 5080-class machine used for local AI inference. The rows are calculator inputs for a node like mine (Ryzen 7 7800X3D, ROG STRIX B650-A, 32GB DDR5, ROG Astral RTX 5080 OC). The wall readings I do have: 80–100 W idle for the whole box, and during inference the card alone draws about 300 W of board power (265–344 W measured across models), which puts the whole box around 350 W. The 85 W input is the low end of my idle range. The 420 W input is an illustrative assumption sustained for each entered active hour, not a measured average or maximum for this machine; replace it with your measured average to estimate your bill.

At the default $0.184/kWh: the calculator returns 1,173 kWh/year — $18/month, $216/year, $647 over 3 years, at a 427W combined load draw.

What electricity rate to use

Read your utility bill. Find the line that shows total kWh used and total charges for the month. Divide total charges by total kWh — that’s your effective rate including all fees and taxes.

The US residential average was $0.184/kWh as of May 2026 per the EIA Electric Power Monthly, and that is the calculator’s default. EIA’s latest month, July 2026, puts it at 18.31 cents (Table 5.6.A, preliminary). The lower figure often quoted is the all-sectors average, 14.99 cents in July 2026, which mixes in cheaper industrial power. Averages also hide wide regional swings. These are the May 2026 residential averages from the same report’s Table 5.6.A:

• Among the cheapest states (Idaho, Utah, Oklahoma): ~$0.12–0.13/kWh
• Missouri (where I’m at): ~$0.137/kWh; Louisiana and Arkansas: ~$0.14/kWh
• New England: ~$0.25–0.29/kWh; California: ~$0.33/kWh
• Hawaii: ~$0.52/kWh

In a high-rate area the cloud delta shrinks for anything running 24/7, because the cloud bill stays the same while the homelab’s electricity cost rises with the rate. The 3-node cluster above (879 kWh/year) costs $264/year at $0.30/kWh, against $162 at the default rate — still well under what three comparable hosted nodes would run.

Time-of-use rates. If your utility offers TOU pricing, use your average blended rate, not the peak rate. Homelabs mostly run at base load overnight when off-peak rates apply.

Sizing a UPS from these numbers

The combined-load result is the sum of the numbers entered, which may be typical workload averages. Do not size a UPS or circuit from the default presets. Record each device’s maximum expected wall draw, include drive spin-up and other simultaneous transients, and compare the resulting load with the UPS’s watt rating and the circuit’s rated capacity. Leave appropriate headroom for your environment.

Battery runtime is a separate check. Use the UPS runtime calculator only within its stated model evidence and load range, or consult the manufacturer’s published runtime curve for the exact UPS and battery condition. The page’s example load totals are not verified UPS sizing recommendations.

Budget Builder connection

The Budget Builder covers upfront component cost — GPUs, NAS units, and networking gear filtered by budget and use case. Use it first to land on hardware, then come back here to model what that hardware actually costs to run. Together they cover hardware and electricity inputs, but not taxes, maintenance, replacement parts, network access or residual value.

For a homelab-versus-cloud decision, pair the electricity delta with dated hardware costs and compare equivalent capacity, service and maintenance over the same period.