Laptop vs desktop electricity: compare the whole workstation

Use the same workload, hours and display arrangement when comparing computers. A power-supply or charger rating is not a measurement of the electricity used throughout a workday.

By HomeCost Radar · Reviewed 2026-09-27 · Editorial policy

Three eight-hour workstation budgets

Assume average wall draw of 30 W for a laptop, 90 W for a desktop tower, and another 25 W for a desktop monitor. A duty of 1 is intentional because these inputs are already average draw. The tower-plus-monitor row treats 115 W as the combined load.

Illustrative sessions at the same Texas electricity rate
Session	Inputs	kWh/session	Cost/session
Laptop including built-in screen	30 W × 8 h × 1 duty	0.2400	$0.04 Range $0.03–$0.06
Desktop tower only	90 W × 8 h × 1 duty	0.7200	$0.12 Range $0.08–$0.17
Desktop plus external monitor	115 W × 8 h × 1 duty	0.9200	$0.15 Range $0.10–$0.22

One session per row. Rates: 2026-07-ytd, published 2026-09-24. The appliance-energy engine prices these assumed loads; the ranges are modeled uncertainty, not product test results. State averages cannot reproduce your utility tariff.

What the example shows: The workdays use 0.240, 0.720 and 0.920 kWh. Comparing the laptop with the complete desktop setup gives a 0.680 kWh difference per workday, or 170 kWh across an assumed 250 workdays.

Account for screens and docks consistently

If your laptop also needs the same 25 W monitor, add 0.200 kWh to its eight-hour budget. Its total becomes 0.440 kWh and the difference from the complete desktop becomes 0.480 kWh. This is why a bare laptop versus a tower-and-two-screens comparison can mislead.

DOE notes that external equipment can change a notebook setup's energy use. Add docks, monitors and speakers when they differ between the setups. Shared equipment can be excluded from both sides only when its operating schedule really is unchanged.

A fair workload may take different amounts of time

For a render, compile or export, compare energy needed to finish the same task. A more powerful machine may draw more watts but finish earlier. For example, a hypothetical 150 W task completed in one hour uses 0.150 kWh, while a 50 W task lasting four hours uses 0.200 kWh.

For office use, an equal-length workday may be a better comparison. Record whether measurements include idle periods, charging a depleted battery or demanding applications, because mixing those states obscures the result.

Include the hours outside the workday

A workstation left idle overnight can consume energy not included in the eight-hour table. Measure sleep, idle and off states separately and make their hours add up to a complete day. Apply each mode once.

Use power-management settings that fit your work and backup requirements. The DOE guidance supports using appropriate low-power modes; it does not make our assumed 30 W or 90 W examples representative of every computer.

Frequently asked questions

Can I use the 650 W rating on my power supply?

That rating describes capacity, not your average workload draw. Use a measured average or a clearly labeled assumption. Otherwise the annual result can be greatly overstated.

Should I add laptop charging to measured wall energy?

Not when charging was already included in the measurement. Adding a separate battery-charge estimate would count some electricity twice.

Sources and assumptions

The worked examples are HomeCost Radar calculations from the stated inputs. Sources below support the concepts identified beside each link; they do not certify our assumed wattages or product savings.

DOE: efficient computers — Computer categories, power management and the effect of external equipment.

EIA Table 5.6.B supplies the state price. Calculation method and uncertainty.