AC Power Calculator
Calculate AC real power for single-phase or three-phase loads.
Interactive Electrical Calculator
AC Power Calculator
Calculate AC real power for single-phase or three-phase loads.
Result
Enter values and calculate.
About the AC Power Calculator
The AC Power Calculator handles total power and load calculations across single-phase, three-phase and AC systems without needing a spreadsheet, app download or manual lookup table. Calculate AC real power for single-phase or three-phase loads. Underestimating total connected load leads to a panel or service that is undersized from day one; overestimating wastes money on oversized equipment.
It's aimed at electricians sizing panels and services, and engineers estimating total connected or demand load, who need a fast, reliable number without redoing the math by hand each time.
How the calculation works
Behind the scenes, the calculation follows:
P = V × I × PF; three phase uses √3 × V × I × PF.
Where each input maps to a field in the calculator above:
- Voltage in V.
- Current in A.
- Power Factor.
- System — choose between Single Phase, Three Phase.
Every one of these values can be edited above, and the calculator updates the result the moment you press Calculate.
A worked example
For example, start with 230 V for voltage, 10 A for current and 0.9 for power factor. Those defaults are only a starting point — replace them with your own measured or nameplate values, then press Calculate to get a result specific to your situation.
When to use the AC Power Calculator
Typical reasons people reach for the AC Power Calculator:
- Estimating total connected load for a new panel or service.
- Comparing single-phase and three-phase power for the same voltage and current.
- Checking a load calculation against a utility service size before requesting an upgrade.
- Sizing equipment for a workshop, small commercial space or off-grid system.
Good practice: Three-phase power calculations use √3 × V × I, not simply 3 × V × I, because of how the phases relate to each other.
Also worth knowing: Diversity and demand factors are usually applied on top of a simple connected-load sum for realistic panel and service sizing.
Frequently asked questions
What does the AC Power Calculator calculate?
Calculate AC real power for single-phase or three-phase loads.
Is the result exact enough to build from?
The formula above is applied exactly to the values you enter, so the math itself is precise. Real-world results can still differ due to component tolerances, temperature, installation method, equipment efficiency and local code requirements, so treat the output as a strong planning estimate and verify final designs against manufacturer data and the electrical code that applies to your installation.
Do I need to sign up or install anything to use it?
No sign-up, download or installation is needed. The AC Power Calculator runs entirely in your browser and is free to use.
Why does this calculation matter in practice?
Power factor changes how much current a given load actually draws, so two loads with the same wattage can need very different conductor and breaker sizes.
Will this work for both metric and everyday values?
The AC Power Calculator works on any modern browser, phone or desktop, and recalculates as soon as you press Calculate. If a result looks off, double-check that every field is filled in with the unit shown next to it (mixing up units, such as W with kW, is the most common cause of an unexpected answer) and re-enter the values.