A/B Testing PC Power Supply Monthly Calculator FAQ
Answers to common questions about PC power supply efficiency, wall power, monthly kWh use, and electricity cost comparisons.
Use these questions and answers to understand the calculator inputs, estimated results, and practical limits of a monthly PC electricity-cost comparison.
General calculator questions
Basic information about what the calculator estimates.
What does this PC power supply calculator compare?
It compares estimated monthly electricity use and cost for two PC load, PSU efficiency, and daily-use scenarios.
What does Scenario B compared with A mean?
It is Scenario B's estimated monthly cost minus Scenario A's. A negative result means B costs less.
Is this an estimate of my complete electricity bill?
No. It estimates electricity associated with the entered PC load and does not include fixed bill charges or unrelated household use.
Inputs and measurements
How to choose the most useful input values.
What should I enter as component load?
Enter the PC components' typical DC demand during the use period being modeled, not the PSU's maximum wattage rating.
How can I measure PC power use?
A suitable plug-in electricity meter can measure wall power. Hardware monitoring and product reviews can help estimate component demand.
Do I include my monitor in component load?
Only if you add its estimated power intentionally. Otherwise, the calculator models the PC load alone.
What electricity price should I use?
Use a relevant per-kWh price from your bill or tariff information. A weighted average may be useful when prices vary by time.
Efficiency and formula questions
How conversion losses are handled.
Why does higher PSU efficiency reduce estimated cost?
A more efficient PSU loses less energy as heat, so it can draw less AC power for the same DC component demand.
Does an 80 Plus rating equal the exact efficiency input?
No. Actual efficiency depends on the specific unit, input conditions, and load level. Use an appropriate estimate for typical use.
Should I set efficiency to 100% for wall-power readings?
Yes. A wall-power reading already includes PSU losses, so using 100% prevents them from being added a second time.
Does PSU capacity determine energy use?
No. Capacity indicates the maximum power a PSU can supply. Actual energy use depends on the PC load, efficiency, and runtime.
Accuracy and use cases
Factors that can cause real results to differ.
Why may actual cost differ from the estimate?
PC load, PSU efficiency, electricity pricing, and active hours can all vary over time.
Can I use this for a gaming PC?
Yes. Use a representative average load for the mix of gaming, menus, idle time, and other tasks you want to model.
Can I estimate annual PC electricity cost?
Multiply a representative monthly estimate by 12, while remembering that usage and rates may change through the year.
Does the calculator include standby electricity?
No, unless standby usage is included in the entered load and hours.
How is PC monthly electricity cost calculated?
Estimated wall kWh is calculated from component load, PSU efficiency, daily use, and days per month, then multiplied by the electricity rate.
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