Watts, amps, and volts equations
The current equation changes with the phase arrangement.
DC: P = V × ISingle-phase: P = V × I × pfThree-phase: P = √3 × VLL × I × pfwhere:
- P
- Active power[W]
- V
- DC or single-phase voltage[V]
- VLL
- Three-phase line-to-line voltage[V]
- I
- Line current[A]
- pf
- Power factor
Use line-to-line voltage for a balanced three-phase load.
How to use the Watts to Amps and Volts Calculator
Power, current, and voltage are shown together. Select the electrical system, choose any two quantities as known inputs, and enter their values; the remaining quantity updates immediately in the result panel.
- Choose DC, single-phase AC, or three-phase AC.
- Select two known quantities from P, I, and V.
- Enter the known values and AC power factor where applicable.
- Read the calculated third quantity in the result panel.
Calculation method and validation
The equations and symbol definitions above show the complete calculation basis. Inputs are checked before calculation so zero, negative, incompatible, or physically impossible combinations are flagged instead of silently producing a misleading result.
How to interpret the result
Use the main result as a starting value and read every supporting metric. Balanced three-phase load Voltage is line-to-line for three-phase A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- Balanced three-phase load
- Voltage is line-to-line for three-phase
Selection limits and next checks
Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions. Compare the output with the current applicable standard, local rules, exact VIOX product datasheet, environmental conditions, protection coordination, and the engineer's project requirements before procurement or installation.
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Assumptions
- Balanced three-phase load
- Voltage is line-to-line for three-phase
Important Warnings
- Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions.