Homelab Power & Cost Calculator

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:

• Idle watts — what the device draws when powered on but not under active load
• Load watts — peak or typical-load draw while VMs are running, drives are spinning up, or the GPU is encoding
• 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: Kill-A-Watt meter. The P3 P4400 ES runs about $30 and reads wattage in real time. Plug your device in, let it boot and settle for 5–10 minutes, then read idle watts. Kick off a benchmark or a Proxmox backup job and read load watts. This gives you actual measured draw for your specific hardware revision.

Second-best: manufacturer TDP and idle specs. Mini PC makers like Beelink and MINISFORUM publish TDP figures on product pages. These are typically accurate for load draw but often optimistic for idle — the chip TDP doesn’t account for the platform, storage, or RAM. Add 5–10W to manufacturer idle figures if you want a conservative estimate.

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

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.

Understanding the outputs

Peak Draw (W) — the sum of all devices at simultaneous full load. This is what your UPS needs to handle and what determines which circuit breaker protects your rack. For UPS sizing, add 20% headroom to this number.

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 TCO — three years of electricity cost. Operating cost only — no hardware amortization. If you want full TCO, add your upfront hardware spend to this figure.

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 configs use measured and manufacturer figures. Plug them in manually or use the presets.

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 $0.13/kWh: ~$7/month, ~$84/year, ~$252 over 3 years. That’s what a basic homelab costs to run. Compare to the cheapest Linode/Vultr 2 vCPU / 4GB VPS at around $24/month — homelab wins at 3 years even before accounting for NAS capacity you’d otherwise pay Backblaze $9/month to access.

Three-node Proxmox cluster

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

At $0.13/kWh: ~$17/month, ~$204/year. 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. This is the configuration my own rig runs — Ryzen 7 7800X3D, ROG STRIX B650-A, 64GB DDR5, ROG Astral RTX 5080 OC.

At $0.13/kWh: ~$14/month at 3 hrs/day GPU load, ~$168/year. Running Llama 3.3 70B locally on the RTX 5080 versus paying $0.002/1K tokens on a hosted API — if you’re generating 500K tokens/day, API costs run $30+/month. Local GPU inference pays back within a few months.

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 average was around $0.132/kWh as of Q1 2026 per the EIA Electric Power Monthly. But averages hide wide regional swings:

• Louisiana, Oklahoma, Arkansas: $0.09–0.11/kWh
• Missouri (where I’m at): ~$0.11–0.12/kWh
• New England, California: $0.20–0.30/kWh
• Hawaii: $0.38+/kWh

If you’re in a high-rate area, the cloud delta math tilts harder toward homelab for anything running 24/7. A 3-node cluster at $0.30/kWh costs $470/year in electricity — 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

Once you have your Peak Draw figure, add 20% for safety margin, then check against the wattage rating (not VA) of any UPS you’re considering.

The UPS sizing guide on this site covers the VA vs W distinction, runtime curves, how to read a load percentage chart, and how to wire NUT into Proxmox so VMs gracefully shut down when battery reaches 30%. Read that before buying.

Quick rule: Peak Draw × 1.2 = minimum UPS wattage rating. For the starter stack (73W peak), a CyberPower CP850PFCLCD (480W capacity) covers it with room to grow. For the GPU workstation (427W peak), you need at minimum a 1000W-class UPS — ideally 1500W for comfortable runtime.

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 give you full TCO: upfront spend plus electricity over the ownership window.

For the homelab-vs-cloud comparison to be honest, pair the cloud delta here with the hardware cost from Budget Builder. That’s the real break-even calculation.