Watts to Volts Calculator
Convert watts to volts using current (amps). The formula is Volts = Watts / Amps. This calculator helps determine the voltage of a circuit when you know the power consumption and current draw.
How to Convert Watts to Volts
- Determine the power consumption in watts (check the device label or specifications).
- Determine the current draw in amps.
- Divide watts by amps to get volts.
- The result is the voltage required by the circuit.
Formula
Volts = Watts / Amps
V = P / I
Where P = power in watts, I = current in amps, V = voltage in volts
Example Calculation
A device uses 1200W and draws 10A. What voltage does it need?
Volts = 1200W / 10A = 120V
A motor uses 3600W and draws 15A:
Volts = 3600W / 15A = 240V
Common Appliance Reference Table
| Appliance | Power | Current | Voltage |
|---|---|---|---|
| LED Light Bulb | 10W | 0.083A | 120V |
| Laptop Charger | 65W | 0.54A | 120V |
| Microwave | 1000W | 8.33A | 120V |
| Hair Dryer | 1500W | 12.5A | 120V |
| Space Heater | 1500W | 6.25A | 240V |
| Electric Oven | 3000W | 12.5A | 240V |
| EV Charger (L2) | 7200W | 30A | 240V |
| Central AC | 5000W | 20.8A | 240V |
Frequently Asked Questions
What is the relationship between watts, volts, and amps?
They are related by Ohm's power law: Watts = Volts x Amps. If you know any two values, you can calculate the third.
Can I use this formula for AC circuits?
For purely resistive AC loads, yes. For inductive or capacitive loads, you need to account for power factor: Volts = Watts / (Amps x Power Factor).
Why do some appliances need 240V instead of 120V?
High-power appliances use 240V to reduce current draw. At 240V, a 4800W dryer draws only 20A instead of 40A at 120V, allowing smaller wiring and safer operation.
What happens if voltage is too low for a device?
Under-voltage causes motors to draw more current to compensate, leading to overheating. Electronics may malfunction or shut down. Prolonged under-voltage can damage equipment.
How is this different from using Ohm's Law?
Ohm's Law (V = I x R) uses resistance. The power formula (V = P / I) uses power. Both give voltage but from different known quantities.