Homelab Power Cost Calculator

Tool · Tools

Last checked: 2026-10-25. Preset figures are copied from official manufacturer spec pages (linked below). Nothing on this page was measured by us.

A home server's running cost is its average power draw times the hours it runs times your electricity price. For example, a device drawing a steady 10 W uses about 88 kWh a year (10 W × 8,760 h ÷ 1000; our arithmetic). Enter idle and load watts, hours at each, and your price per kWh to get daily, monthly and yearly cost.

This calculator turns a device's power draw into energy use (kWh) and cost. Enter how many watts the box draws when idle and under load, how many hours a day it spends in each state, and your electricity price. Pick a currency symbol to label the result. There is no currency conversion: enter the price in your own currency per kWh.

Calculator

The live calculator needs JavaScript. It runs only in your browser and sends nothing. Without JavaScript, use the formula and tables below: they give the same results by hand.

The formula

text

kWh per day   = (idle W × idle hours + load W × load hours) ÷ 1000
kWh per month = kWh per day × 365 ÷ 12
kWh per year  = kWh per day × 365
cost          = kWh × your price per kWh

Idle hours plus load hours should add up to 24 for a box that is always on.

Worked example (example price, not a real tariff): a Synology DS225+ at its "Access" figure of 16.98 W for 8 hours and its "HDD Hibernation" figure of 6.08 W for 16 hours, at an example price of $0.15/kWh:

(6.08 × 16 + 16.98 × 8) ÷ 1000 = (97.28 + 135.84) ÷ 1000 = 0.233 kWh per day
0.233 × 365 ÷ 12 = 7.09 kWh per month, about $1.06 at $0.15
0.233 × 365 = 85.1 kWh per year, about $12.76 at $0.15

Presets from official spec pages

Only devices whose maker publishes a power-consumption figure are listed. Synology publishes two figures per model: "Access" and "HDD Hibernation". The calculator uses Access as the load figure and HDD Hibernation as the idle figure. These are Synology's own test figures (see Synology's note on how they are measured, linked from each spec page), not our measurements, and real draw depends on your drives and workload.

Device	Access (W)	HDD Hibernation (W)	Source (checked 2026-10-25)
Synology DS124	10.69	3.44	https://www.synology.com/en-global/products/DS124#specs
Synology DS223j	16.31	4	https://www.synology.com/en-global/products/DS223j#specs
Synology DS225+	16.98	6.08	https://www.synology.com/en-global/products/DS225+#specs
Synology DS425+	28.25	6.10	https://www.synology.com/en-global/products/DS425+#specs

Mini PCs are not in the preset list. We checked the official pages for the Beelink EQ14, GMKtec NucBox G3 Plus, Minisforum M1 Pro-125H and the Lenovo PSREF sheet for the ThinkCentre M70q Gen 5, and found no published idle or load wall-power figure. A CPU's TDP or the power adapter rating is not the same as wall power, so we do not use them. Enter your own figures (for example from a plug-in power meter).

Annual energy and cost at an example price

Example price: $0.15/kWh. This is an illustration, not a real or average tariff. Each row assumes the box stays in one state for 24 hours a day, 365 days a year, so a real mix of idle and load falls between the two columns.

Device	All year at Access	Cost at $0.15	All year at HDD Hibernation	Cost at $0.15
Synology DS124	93.6 kWh	$14.05	30.1 kWh	$4.52
Synology DS223j	142.9 kWh	$21.43	35.0 kWh	$5.26
Synology DS225+	148.7 kWh	$22.31	53.3 kWh	$7.99
Synology DS425+	247.5 kWh	$37.12	53.4 kWh	$8.02

Limits

The presets are maker figures, not measurements. Drive count and model, fans, attached USB devices and your workload all change real draw.
A plug-in power meter on your own box is the most accurate input.
Prices often have fixed charges, tiers and time-of-use rates. This calculator uses a single price per kWh.