How much electricity does a mini PC use? The useful answer is the power your complete computer draws at the socket during your own work, multiplied by the time it spends doing that work. A processor's TDP or the wattage printed on a power adaptor cannot give you that answer on its own.

This guide shows you how to measure mini PC power consumption, separate the computer from the rest of your desk, and turn readings in watts into energy in kilowatt-hours. The numerical examples are hypothetical calculations, not measurements of a GMKtec model or promised savings.

Understand the three different power figures

Before comparing computers, check what each number describes. Three figures can all use watts while answering different questions.

Intel's explanation of TDP describes its role in thermal design and notes that some workloads can exceed the stated processor value. It is not a measurement of your complete mini PC, its adaptor and its peripherals.

For example, an adaptor labelled 120 W does not mean the computer uses 120 W throughout an eight-hour day. Do not replace the supplied adaptor with a lower-rated one as an energy-saving experiment.

Decide whether you are measuring the PC or the whole desk

For a PC-only reading, put the energy meter between the wall socket and the mini PC's power adaptor. This includes the adaptor's conversion losses and any accessories powered through the computer. A monitor powered from a separate socket is outside that measurement.

For a whole-desk reading, a suitably rated meter can measure a compatible power strip supplying the PC, monitor and other desk equipment. Follow the meter and power strip instructions, keep within their ratings, and record every connected item. Do not compare that result with another review's PC-only figure.

A USB-powered drive belongs inside the PC measurement when the PC supplies its power. A separately powered dock or external GPU needs its own measurement or inclusion in the desk total. If a monitor supplies power to a compatible computer, record that different power path explicitly.

Keep display settings consistent between runs. Our mini PC multiple-monitor guide helps you establish the connection arrangement before starting the comparison.

Measure a normal working day

Use a plug-in energy meter suitable for your local sockets and supply, with a watts display and preferably a cumulative kWh counter. Check its measurement range and accuracy, particularly at low loads. As one example, Brennenstuhl's meter specifications state both a minimum measuring range and an accuracy allowance. A display rounded to zero is not proof of exactly zero consumption.

1. Finish initial setup. Complete your normal updates and restart first. Use our mini PC first-boot guide if the computer is new. Avoid treating the first update-heavy hour as everyday idle behaviour.
2. Write down the setup. Record the exact model, RAM and SSD, Windows power mode, connected accessories, display arrangement and whether the meter covers the PC or the desk.
3. Connect with the computer shut down. Follow the meter's instructions and use the supplied PC adaptor. Use intact, correctly rated equipment; no opening of the adaptor or mains wiring is needed.
4. Check distinct states. Record settled desktop idle, representative work, your demanding task, and sleep or shutdown. Note background activity rather than forcing every fluctuating reading into one number.
5. Record energy over time. Note the starting and ending kWh counter and the elapsed hours. A representative day captures changing workloads better than one momentary peak. Repeat when your usage varies.

Keep a simple log:

For a completed job, compare both energy and completion time. A lower instantaneous wattage does not settle the comparison if the same job takes substantially longer. For an always-on system, include the many hours between active tasks rather than extrapolating from peak load.

Convert watts and hours into kWh

Watts measure the rate of electricity use; kilowatt-hours measure the accumulated energy. The Energy Saving Trust's guide to energy units distinguishes these terms.

Energy (kWh) = average power (W) × time (hours) ÷ 1,000.

If a meter records 0.18 kWh over six hours, the average power for that interval is 0.18 × 1,000 ÷ 6 = 30 W. That average is more useful for that session than the highest number you happened to see.

A worked example with different daily states

The following values are invented solely to demonstrate the arithmetic. They are not typical-use figures, a benchmark, or specifications for any product.

If this exact pattern repeated for 30 days, it would use 8.76 kWh. Replace every assumed wattage and time with your own observations. For different weekdays and weekends, calculate those patterns separately before adding them.

Estimate the electricity charge using your own tariff

Usage charge = energy (kWh) × your price per kWh. The Virginia Cooperative Extension energy-use guide documents this calculation. Use your current tariff in euros per kWh; convert cents to euros first where needed. On a time-of-use tariff, calculate each tariff period separately. This estimates the measured equipment's usage charge, not your complete household bill or fixed charges.

Reduce unnecessary running time, then measure again

Start with the time the computer spends awake without a useful task. In Windows 11, open Settings, then System, and look for the power settings. Review the screen-off and sleep timers using Microsoft's Windows 11 power settings guide. Choose intervals that suit your work and test wake-up with your usual devices.

Turning off a display and putting the computer to sleep are separate actions. Microsoft's sleep and hibernation guidance explains the available states and notes that hibernation is not offered on every PC.

If the computer must host files, run a scheduled job or remain remotely accessible, confirm that the required service still works with your chosen settings. Change one setting at a time, repeat the same workload, and compare both energy use and usability. Keep firmware power limits at their documented settings unless the manufacturer provides instructions for your exact model.

Compare mini PCs with a consistent checklist

Before relying on a published wattage, look for the tested configuration, power mode, workload, measurement boundary and duration. If these are missing, treat the number as incomplete context rather than a universal figure for that processor or product family.

For your own shortlist, begin with the applications, memory, storage and display support you need. Then assess documented energy measurements under comparable conditions. Browse the GMKtec EU mini PC collection to compare configurations, and keep this measurement checklist alongside your specification checklist when setting up your next system.