Volts to Amps Calculator
Convert voltage to amperage using wattage. Enter the voltage in volts and power in watts to calculate the current in amps. Works for all AC and DC circuits.
How to Convert Volts to Amps
The formula to convert volts to amps is: Amps = Watts ÷ Volts.This is derived from the power equation P = V × I, rearranged to solve for current (I = P ÷ V). You need to know the wattage of the device or load — voltage alone cannot tell you the amperage.
Formula: A = W ÷ V
Alternative (with resistance): A = V ÷ Ω
For example, a 1,800-watt appliance running on a 120-volt circuit draws 15 amps (1800 ÷ 120 = 15). The same appliance at 240 volts would draw only 7.5 amps — this is why higher voltages are used for large appliances, as they reduce current and allow for smaller wire gauges.
If you know the resistance in ohms instead of watts, you can use Ohm's Law: Amps = Volts ÷ Ohms.
Volts to Amps Conversion Chart
Amperage for common wattage and voltage combinations:
| Watts | @ 12V (DC) | @ 120V | @ 240V | @ 480V |
|---|---|---|---|---|
| 50 W | 4.17 A | 0.42 A | 0.21 A | 0.10 A |
| 100 W | 8.33 A | 0.83 A | 0.42 A | 0.21 A |
| 200 W | 16.67 A | 1.67 A | 0.83 A | 0.42 A |
| 500 W | 41.67 A | 4.17 A | 2.08 A | 1.04 A |
| 750 W | 62.50 A | 6.25 A | 3.13 A | 1.56 A |
| 1,000 W | 83.33 A | 8.33 A | 4.17 A | 2.08 A |
| 1,500 W | 125.00 A | 12.50 A | 6.25 A | 3.13 A |
| 2,000 W | 166.67 A | 16.67 A | 8.33 A | 4.17 A |
| 3,000 W | 250.00 A | 25.00 A | 12.50 A | 6.25 A |
| 4,000 W | 333.33 A | 33.33 A | 16.67 A | 8.33 A |
| 5,000 W | 416.67 A | 41.67 A | 20.83 A | 10.42 A |
| 7,500 W | 625.00 A | 62.50 A | 31.25 A | 15.63 A |
| 10,000 W | 833.33 A | 83.33 A | 41.67 A | 20.83 A |
Frequently Asked Questions
How do you convert volts to amps?
Divide watts by volts to get amps. The formula is: Amps = Watts ÷ Volts. For example, a 1,800-watt appliance at 120 volts draws 15 amps (1800 ÷ 120 = 15). You need to know the wattage (power) to convert volts to amps — voltage alone is not enough.
How many amps is 120 volts?
You cannot convert volts to amps without knowing the wattage. 120 volts could be any amperage depending on the load. For example, a 60W light bulb at 120V draws 0.5 amps, while a 1,500W space heater at 120V draws 12.5 amps. Both use 120V but draw very different amperages.
How many amps does a 1500 watt heater draw at 120V?
A 1,500-watt heater at 120 volts draws 12.5 amps (1500 ÷ 120 = 12.5). This is why space heaters are often the largest load on a 15-amp circuit and should ideally be on a 20-amp dedicated circuit for continuous operation per the NEC 80% rule.
How many amps is 240 volts?
The amperage at 240 volts depends entirely on the wattage of the load. At 240V, a 4,800W water heater draws 20 amps (4800 ÷ 240 = 20), while a 10,000W electric range draws 41.67 amps. Higher voltage means lower amperage for the same wattage.
Why do you need watts to convert volts to amps?
Voltage alone doesn't determine current flow — the load (power consumption) does. Ohm's Law states that current (amps) equals power (watts) divided by voltage (volts): I = P ÷ V. Without knowing the power consumed, there's no way to calculate the current. If you know resistance instead of watts, use Amps = Volts ÷ Ohms.
How many amps does a 100-watt light bulb draw?
At 120V, a 100-watt light bulb draws 0.83 amps (100 ÷ 120 = 0.83). This is why you can safely run many light bulbs on a single 15-amp circuit — fifteen 100W bulbs would draw about 12.5 amps, still within the circuit's capacity.
What is the relationship between volts, amps, and watts?
Watts = Volts × Amps. These three values form the power triangle. If you know any two, you can calculate the third: Amps = Watts ÷ Volts, Volts = Watts ÷ Amps, Watts = Volts × Amps. This relationship is fundamental to all electrical calculations.
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