Converting watts to amps is fairly easy. In most cases, you will have to divide watts by voltage (V) to get amps. The Watts To Amps Calculator will help you with the conversion for any current type (DC, AC 1-phase, or AC 3-phase current).
Below the calculator, we feature 3 examples that illustrate how to make this conversion. You can freely use the calculator here (you can play around with the numbers a bit):
Let’s use this calculator to show how to calculate watts to amps for DC current (mostly batteries), AC 1-phase current (most common in our electrical outlets), and AC 3-phase current (for high voltage equipment):
DC Watts To Amps (For Batteries)
All batteries use DC current (Direct Current). We usually use 12-volt batteries (such as 12V LiFePO4), but you also have 6V, 24V, and 48V batteries.
The formula for converting watts to amps for DC current is the following:
Amps (DC) = Watts / Volts
For DC current (amps), we simply divide watts by volts to get the amps.
12 Volt DC Watts To Amps Example:
Suppose we have a 12V battery that gives us 600 watts of power. How many amps does it draw? Here is the calculation:
Amps (DC) = 600 Watts / 12 Volts = 50 Amps
We can use the calculator above to get the same result:
We see that 600 watts on a 12V DC battery draws 50 amps.
Single-Phase AC Watts To Amps
AC 1-phase is the standard current we probably all have in our homes. The most common voltages here are 120 Volts in the US, and 220 Volts or 240V in Europe.
The formula for converting 1-phase AC watts to amps is as follows:
Amps (1-Phase AC) = Watts / (Volts × Power Factor)
You can see that we have to account for the Power Factor (PF). This is a parameter between 0 and 1. Luckily, in more than 99% of cases, you can set the Power Factor at 1.00. As we will see further on, the Power Factor really comes into play for 3-phase AC current.
For 1-phase AC current (amps), we have to divide watts by both volts and power factor like this:
1-Phase AC Watts To Amps 120V Example:
Let’s say you are running a 1500-watt space heater on the standard 120V voltage. The Power Factor (PF) is 1.00. How many amps does it draw? Let’s calculate 120V 1500W to amps like this:
Amps (1-Phase AC) = 1500 Watts / (120 Volts × 1) = 12.5 Amps
You can use the calculator above to do this calculation automatically. Here is the screenshot:
We see that the 120V 1500W space heater draws 12.5 amps. If, however, we have a 240V voltage, the amps are reduced (halved). A 240V 1500W space heater would draw 6.25 amps (you can check this with the calculator above).
AC 3-Phase Watts To Amps (High Voltage Devices)
3-phase AC current is used by high-voltage devices, such as power generators, motors, and so on. With a 3-phase AC current, you usually have higher voltages: 208V or 240V in the US, and 440V and 480V in Europe.
Here, we don’t use the standard voltage. For 3-phase AC, we have to use RMS voltages; there are 2 types (line to line RMS voltage (VL-L), and line to neutral RMS voltage (VL-N)). Hence, we have these 2 separate formulas for each of the RMS voltages types:
Amps (3-Phase AC Line-To-Line) = Watts / (√3 × Power Factor × VL-L)
Amps (3-Phase AC Line-To-Neutral) = Watts / (3 × Power Factor × VL-N)
Admittedly, these are more complex equations that electricians and engineers use more often. As we can see, if we have a line-to-line RMS voltage, we can calculate amps by dividing watts by a square root of 3 (about 1.732), power factor, and line-to-line RMS voltage.
If you have a line-to-neutral RMS voltage, we can calculate amps by dividing watts by 3, power factor, and line-to-neutral RMS voltage.
Expert Tip: Notice the difference between using a square root of 3 for line-to-line RMS voltage and using just a factor of 3 for line-to-neutral RMS voltage. It is a small but important difference.
3-Phase Watts To Amps Line-To-Line Example:
Let’s say we have a 3000-watt electric device running on 240V line-to-line voltage. The power factor is 0.8. Here is how to calculate the amps for this device:
Amps (3-Phase AC Line-To-Line) = 3000 Watts / (√3 × 0.8 × 240 Volts) = 9.021 Amps
We can all admit that typing all this in a hand calculator is a bit tedious. That’s why using the general watts to amps calculator above is so much easier, especially for 3-phase AC current (screenshot for this calculation):
We can again see that a 3000W 240V line-to-line voltage electrical device at 0.8 power factor draws about 9 amps (9.021 amperes, to be exact).
Here are some of the watts to amps FAQ to help you out. You can pose more questions in the comments below, give us some numbers, and we’ll help you out:
Amps Explained
Amp or Ampere is the most widely used unit of electric current. Electric current is simply a flow of electrically charged particles. In most cases, we are dealing with negatively charged electrons (e–) moving inside the wires.
1 ampere equals an electric charge of 1 Coulomb (unit of electric charge) moving for 1 second of time.
Watts Explained
In electrical devices, watt is the commonly used unit of electric power. A watt is equal to electric power produces by a current of 1 amp across 1 volt of electrical potential difference. That’s why we also say that watt is equal to volt-amps.
Volts Explained
A volt is a unit of electrical potential difference. The more volts of a potential difference you have (12V is small voltage, 120V is standard voltage, 240V can be considered high voltage), the more quickly the electrons in the wire flow.
That’s why you can decrease the amps by increasing voltage (to get the same power output or wattage).
What Are Typical Power Factors For 3-Phase AC Current?
Here is a short list of typical power factors for electrical devices:
| Type of Electric Device | Power Factor |
| Resistive load (electric heaters, incandescent lamps…) | 1 |
| Incandescent lamps | 1 |
| Fluorescent lamps (uncompensated) | 0.5 |
| Fluorescent lamps (compensated) | 0.93 |
| Discharge lamps | 0.4 – 0.6 |
| Ovens using resistance elements | 1 |
| Induction heating ovens (compensated) | 0.85 |
| Dielectric type heating ovens | 0.85 |
| Common Induction Motor loaded at 0% | 0.17 |
| Common Induction Motor loaded at 25% | 0.55 |
| Common Induction Motor loaded at 50% | 0.73 |
| Common Induction Motor loaded at 75% | 0.8 |
| Common Induction Motor loaded at 100% | 0.85 |
According to: https://www.electrical-installation.org/enwiki/Practical_values_of_power_factor
Specific Watts To Amps Conversions
To help everybody out as much as possible, we have created a bunch of specific watts to amps conversion. Here are the main ones:
| 1 Watt To Amps | 200 Watts To Amps |
| 10 Watts To Amps | 500 Watts To Amps |
| 20 Watts To Amps | 1000 Watts To Amps |
| 50 Watts To Amps | 1500 Watts To Amps |
| 100 Watts To Amps | 4500 Watts To Amps |
With this online watts to amps calculator, solved examples, and specific examples, you now have all you need to make this conversion. If you need any help, you can use the comment section below, give us some numbers, and we can help you with the math.
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