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How Many Amps is 5 Watts? – A Quick & Easy Guide

Written by Edwin Jones / Fact checked by Andrew Wright

how many amps is 5 watts

Understanding the relationship between amps, watts, and voltage is essential for anyone using an electrical system. In such cases, you may want to know, “How many amps is 5 watts?”

This article aims to provide a range of conversion formulas suitable for different electrical systems. With this knowledge, you can easily determine the required current for your specific appliances.

Calculating Amps from Watts


When understanding electrical systems, calculating the number of amps from watts is a valuable skill. The process of amperage conversion depends on various factors, such as the type of electrical systems, namely DC, AC Single-Phase, and two types of Three-phase systems: the line-to-line voltage and line-to-neutral voltage connection.

Furthermore, converting watts to amps depends on specific voltage rating and formulas. Here is how to convert 5 watts to amps in different systems.

1. Direct Current (DC)

In DC systems, the formula would be Amps = Watts / Volts. As you can see, the calculation is relatively straightforward. Simply divide the number of watts by the voltage in volts. Let’s consider an example: if you have 5 watts of power at a voltage of 120 volts DC, the calculation would be:

\[ \text{Amps} = \frac{5 \text{ watts}}{120 \text{ volts}} = 0.041 \text{ amps} \]

2. Alternating Current (AC), Single-Phase

Converting 5w to amps in AC systems requires an additional factor known as the power factor. This number represents the efficiency of the AC system and can vary depending on the type of load.

The formula and calculation for this type of electrical system is Amps = Watts / (Volts x Power Factor).

Suppose you have 5 watts of power at 220v with a power factor of 0.8. The calculation would be:

\[ \text{Amps} = \frac{5 \text{ watts}}{220 \text{ volts}} \times 0.8 = 0.028 \text{ amps} \]

Therefore, in an AC system with 5 watts, 120 volts, and a power factor of 0.8, the current would be approximately 0.052 amps.

3. Three Phase AC Systems

In three-phase systems, you must first know their line connections. This is because AC three-phase line-to-line voltage differs from AC three-phase line-to-neutral voltage. For these connections, here are their formulas and calculations.

  • AC three-phase line-to-line

For line-to-line connections, the formula will be Amps = Watts / (√3 x PF x V). Suppose you have 5 watts of power and 0.8 power factor at a line-to-line voltage of 208 volts; the calculation will be:

\[ \text{Amps} = \frac{5 \text{ watts}}{\sqrt{3} \times 0.8 \times 208 \text{ volts}} = 0.017 \text{ amps} \]

  • AC three-phase line-to-neutral

For line-to-neutral connections, the formula will be Amps = Watts / (3 x PF x V). Suppose you also have 5 watts of power and 0.8 power factor plus a line-to-neutral voltage of 240 volts; the calculation will be:

\[ \text{Amps} = \frac{5 \text{ watts}}{3 \times 0.8 \times 240 \text{ volts}} = 0.0086 \text{ amps} \]

Understanding calculations for various current ratings at different voltage levels of an electrical system will allow you to determine the number of amps accurately. Aside from this manual calculation, you can also find an online calculator offering straightforward conversion of watts to amps.


In conclusion, knowing how many amps is 5 watts requires being specific about the voltage and type of electrical system you have. Then you can use the suitable formula for converting power into current.

To ensure the safety of the circuit, your appliances must not overload or exceed its rating. This way, electronic equipment can work properly without experiencing any problems.

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