electrical tool
Volts Amps Watts Calculator
Solve for the missing volts, amps, or watts value.
Choose one unknown. For three-phase AC, voltage is line-to-line voltage.
Calculated watts
1080 W
The result uses the selected system type and power factor.
Electrical relationship guide
How volts, amps, and watts relate
Voltage is electrical potential, amps are current, and watts are real power. This calculator lets you choose the unknown and keeps the other values visible so the relationship is easy to check.
Core formulas
Find power
P = V × I
Find voltage
V = P ÷ I
Find current
I = P ÷ V
Worked examples
Power: 120 V × 10 A = 1,200 W.
Voltage: 1,500 W ÷ 12.5 A = 120 V.
Current: 2,400 W ÷ 120 V = 20 A.
AC considerations
For AC loads, select the appropriate system type and provide power factor when applicable. Single-phase AC uses P = V × I × PF. Three-phase AC uses P = √3 × V × I × PF, with line-to-line voltage as the input assumption.
Practical uses
Use the relationship to check a nameplate, translate a known load into current, estimate power from a current measurement, or cross-check another electrical calculation. Results are estimates and should be checked against equipment documentation.
Frequently asked questions
What is the basic volts, amps, and watts relationship?
For a simple DC or unity-power-factor case, power equals voltage multiplied by current: P = V × I.
How do I solve for volts?
When power and current are known, divide power by current: V = P ÷ I.
How do I solve for amps?
When power and voltage are known, divide power by voltage: I = P ÷ V.
When do AC calculations need power factor?
Use power factor for AC loads when it is relevant or available from the equipment documentation. Three-phase AC also uses the √3 phase factor in this calculator.
Important assumptions
This is a planning estimate, not a guarantee of performance. Real equipment varies with temperature, age, power quality, duty cycle, wiring, and manufacturer specifications.