Wattage to Amperage Calculator
Convert watts to amps for DC, AC single-phase, and AC three-phase circuits using the I = P/V formula. Free online wattage-to-amperage calculator with interactive comparison charts and step-by-step breakdowns.
About This Calculator
The Wattage to Amperage Calculator converts electrical power (watts) to current (amps) for DC, AC single-phase, and AC three-phase circuits. Whether you're sizing circuit breakers, selecting wire gauges, designing solar panel systems, or troubleshooting electrical equipment, this tool gives you instant current values from your power and voltage inputs.
The calculator applies Ohm's law power formula P = V × I, rearranged as I = P / V for DC circuits. For AC circuits, it accounts for power factor: I = P / (V × PF) for single-phase, I = P / (√3 × V × PF) for three-phase line-to-line, and I = P / (3 × V × PF) for three-phase line-to-neutral connections. The interactive charts show how current varies across standard voltage levels (110V–240V) and different connection types, helping you understand the relationship between power, voltage, and current at a glance.
Regional Notes
India: Standard household voltage is 230V at 50 Hz. Most residential circuits are single-phase, while industrial and commercial buildings use three-phase 415V line-to-line. Common appliance ratings range from 50W (ceiling fan) to 2000W (air conditioner, water heater). Always verify your local voltage before sizing breakers and wires.
United States: Standard household voltage is 120V for general outlets and 240V for large appliances (dryers, ovens, EV chargers) at 60 Hz. Most homes use split-phase 120/240V service. The National Electrical Code (NEC) requires continuous loads to be calculated at 125% of the rated current for breaker sizing.
United Kingdom: Standard voltage is 230V at 50 Hz, single-phase for homes and three-phase for commercial/industrial installations. BS 7671 (IET Wiring Regulations) governs electrical installations. Typical appliance ratings: 2000–3000W for ketters and heaters, 700–1200W for microwaves, 500–1500W for vacuum cleaners.
Frequently Asked Questions
How do you convert wattage to amperage?
For DC circuits, divide power (watts) by voltage (volts) using the formula I = P / V. For AC single-phase circuits, include the power factor: I = P / (V × PF). For AC three-phase line-to-line, use I = P / (√3 × V × PF), and for line-to-neutral use I = P / (3 × V × PF).
How many amps is 1500 watts at 120 volts?
At 120 volts DC, 1500 watts equals 12.5 amps (I = 1500 / 120 = 12.5 A). For AC single-phase with a 0.9 power factor, it would be 1500 / (120 × 0.9) = 13.89 amps.
What is the difference between wattage and amperage?
Wattage (watts) measures electrical power — the rate of energy consumption or production. Amperage (amps) measures electrical current — the flow of electric charge. They are related by the formula P = V × I, where V is voltage in volts.
How do you calculate amps from watts for a 230V circuit?
For a 230V DC circuit, divide the wattage by 230. For example, 2000W at 230V DC gives 8.70 A (I = 2000 / 230 = 8.70 A). For AC circuits, also divide by the power factor.
What is power factor and why does it matter for AC circuits?
Power factor (PF) is the ratio of real power (watts) to apparent power (volt-amps) in an AC circuit, ranging from 0 to 1. It matters because only real power does useful work, but the current drawn depends on both real power and PF. A lower PF means higher current for the same power, requiring larger wires and breakers.
Is there a difference between DC and AC amperage calculation?
Yes. For DC circuits, amps = watts / volts directly. For AC circuits, you must account for power factor: amps = watts / (volts × PF). Three-phase AC adds a √3 factor for line-to-line or 3 for line-to-neutral connections.
How do I use this calculator for three-phase circuits?
Select AC Three Phase (Line-to-Line) or AC Three Phase (Line-to-Neutral) from the Current Type dropdown. Enter the total power in watts, the line-to-line or line-to-neutral voltage, and the power factor (typically 0.8 to 0.95 for motors). The calculator will apply I = P / (√3 × V × PF) or I = P / (3 × V × PF).
Can I share my wattage to amperage calculation results?
Yes, the URL automatically saves your input values so you can bookmark, share, or revisit the exact calculation anytime. All inputs are preserved in the URL parameters.