Volts and Amps to Watts Calculator

Here is simple volts and amps to watts calculator with short explanations, formulas, and charts.

Unit conversions sometimes can be difficult, but with most basic electric units like the voltage, current, and power, things are almost always very simple. Almost always...

Updated: September 2, 2024.

Amps and Volts to Watts and Other Conversion Calculators

In order to convert volts, amps, and watts, feel free to use these conversion calculators - write the values that You have and click 'Calculate' to convert them:

How to Convert Volts and Amps to Watts and Other Formulas

In order to convert volts, amps, and watts, we need to use these formulas:

• P (W) = I (A) * U (V)
• I (A) = P (W) / U (V)
• U (V) = P (W) / I (A)

Note: these formulas are for either DC (Direct Current) electric systems or for AC (Alternate Current) electric systems using 'effective' values and ϕ=0° (ϕ is the phase angle between voltage and current, sometimes also labeled as "α").

In alternating current (AC) systems, the relationship between amps, volts, and watts is not as straightforward as in direct current (DC) systems because of the phase difference between the voltage and the current, and the concept of power factor comes into play.

Converting Amps and Volts to Watts in AC Systems

The basic formula to find the power in watts in an AC system is:

• P (W) = U (V) * I (A) × PF

Where:

• P(W) is the power in watts,
• U(V) is the voltage in volts,
• I(A) is the current in amperes,
• PF is the power factor.

Power Factor (PF)

Power Factor is a measure of how effectively the electrical power is being used, and it is a very important concept in AC circuits. The power factor can range from 0 to 1, and it reflects the efficiency of the electrical system.

A power factor of 1 means that all the power is being effectively used to do useful work (such as turning a motor), whereas a lower power factor indicates that some of the power is wasted.

The power factor is defined as the cosine of the phase angle (ϕ) between the current and voltage waveforms. In mathematical terms:

• PF = cos⁡(ϕ)

In practical scenarios, the phase angle arises due to the inductive or capacitive nature of the load.

Inductive loads (like motors and transformers) cause the current to lag behind the voltage, while capacitive loads (like capacitor banks) cause the current to lead the voltage.

Types of Power in AC Systems

• Real Power (P): This is the actual power consumed by the devices to perform work. It is measured in watts (W).
• Reactive Power (Q): This power is used to establish the electric and magnetic fields in inductive and capacitive loads. It is measured in volt-amperes reactive (VAR).
• Apparent Power (S): This is the product of the RMS voltage and RMS current, representing the total power in the circuit without considering the phase angle or power factor. It is measured in volt-amperes (VA).

The relationship between these types of power can be expressed through the formula:

• S² = P² + Q²

or:

• S = √(P2 + Q2)

Where:

• S is the apparent power in volt-amperes,
• P is the real power in watts,
• Q is the reactive power in volt-amperes reactive.

Formula Recap

To summarize, the key formulas in AC power calculations are:

• Watts (Real Power): P (W) = U(V) * I (A) × PF
• Apparent Power: S (VA) = U(V) * I(A)
• Power Factor: PF=cos⁡(ϕ)
• Reactive Power: Q (VAR) = S × sin⁡(ϕ)

Understanding these concepts and how they interrelate is essential for effectively designing and managing AC electrical systems.

3-Phase AC Volts and Amps to Watts Calculation Formula

In three-phase AC systems, calculating the power in watts involves a few additional considerations compared to single-phase systems.

The formula used depends on whether the three-phase system is connected in a "star" (Y) or "delta" (Δ) configuration and whether line-to-line (V_L) or line-to-neutral (V_N) voltages are known.

Here’s how to calculate the power in three-phase systems:

Three-Phase Power Calculation Formulas

For a Balanced Load: Assuming the load is balanced (common in most practical scenarios), the formulas are simplified:

• Using Line-to-Line Voltage:

P = √3 * V_L * I * PF

• Using Line-to-Neutral Voltage:

P = 3 * V_N * I * PF

Where:

P is the total power in watts.

• V_L​ is the line-to-line voltage in volts.
• V_N​ is the line-to-neutral voltage in volts.
• I is the current in amperes (assumed to be the same in each phase).
• PF is the power factor, a dimensionless number between 0 and 1.

Explanation of Variables

• Line-to-Line Voltage (V_L): This is the voltage measured between any two of the three phases.
• Line-to-Neutral Voltage (V_N): This is the voltage measured between any one phase and the neutral point (in a star configuration).
• Current (I): In a balanced system, the current is the same in each phase and is typically measured per phase.
• Power Factor (PF): As in single-phase systems, this represents the efficiency of the power usage, factoring in the phase difference between the voltage and the current.

Why Use These Formulas?

• √3​: The factor of √3 (approximately 1.732) comes into play in three-phase power calculations. This factor is vital for converting between the phases and correctly accounting for the entire system's power usage.
• Balanced Loads: These formulas assume that the system is balanced, which means that the power, voltage, and current are equal in each phase and symmetrically phased out by 120 degrees. This assumption simplifies calculations and is typical for most commercial and industrial electrical systems.

Example Calculation

If you know the line-to-line voltage is 480 volts, the current per phase is 10 amperes, and the power factor is 0.95 in a three-phase system, the total power would be calculated as follows using the line-to-line voltage formula:

P = √3 * 480 V * 10 A * 0.95 = 7898 W

This method provides a straightforward way to estimate the total power consumption in a three-phase electrical system, considering the phase interactions and the efficiency of the system reflected by the power factor.

Volts to Watts Chart

The following chart lists the Watts of the electrical system for various voltages and Amps, assuming Power Factor to be 1 in a single-phase electric system - also equivalent to the DC electric system.

Thus, if you want to convert, for example:

12V to Watts:

If the current is, for example, I=5A @12V, that is 60W.

18V to Watts:

If the current is, for example, I=10A @18V, that is 180W.

20V to Watts:

If the current is, for example, I=3A @20V, that is 60W.

24V to Watts:

If the current is, for example, I=10A @20V, that is 200W.

36V to Watts:

If the current is, for example, I=25A @36V, that is 900W.

48V to Watts:

If the current is, for example, I=8A @48V, that is 384W.

120V to Watts:

If the current is, for example, I=5A @120V, that is 600W.

230V to Watts:

If the current is, for example, I=2A @230V, that is 460W.

If you can't find the value in the chart, please use conversion calculators.

1500 Watts to Amps and Volts

When converting 1500 Watts to Amps and Volts, one has to know the actual voltage of the system. The following chart lists required Amps for several very common voltages found in cars, power inverters, RVs, in marine applications, at homes, etc.

The stronger the current, the thicker the cable is required to keep the energy losses at acceptable levels.

2000 Watts to Amps and Volts

If You plan on having a 2000 Watts load (power generator, power inverter, UPS device, etc.), it is recommended to know the required current (A or Amps) and voltage (V) - the higher the voltage, the less current is required, leading to thinner cables or less energy loses. However, higher voltages can be harmful.

The following chart lists the required Amps and Voltages for the required 2000 watts of power.

As one can see, if the nominal voltage is increased from 12V to 48V, the current is decreased 4x, leading to a rather acceptable current of 41.66 Amps (from 166.6A!).

3000 Watts to Amps and Volts

Similarly, if the load is 3000W or even larger, higher voltages are required in order to keep the current at acceptable levels:

In order to find the exact voltages, currents, and wattages, feel free to use our conversion calculators.

Watts, Volts, and Amps Conversion Frequently Asked Questions (FAQ)

Here are the most common Frequently Asked Questions (FAQ) about electric unit (Volts, Amperes, Watts) conversions:

How to calculate Amps from Watts and Volts?

To calculate the current in the electric circuit from Watts and Volts, use the following formula:

I(A) = P(W) / U(V)

How to calculate Watts from Volts and Amps?

To calculate the power in the electric circuit from Amps and Volts, use the following formula:

P(W) = I(A) x U(V)

How to calculate Volts from Watts and Amps?

To calculate the voltage in the electric circuit from Watts and Amps, use the following formula:

U(V) =P(W) / I(A)

How many Watts are 240 Volts?

If we know the voltage of the electric circuit, to calculate the circuit's power, we must find out the electric current (A) in the electric circuit.

For example, if the current is 3 Amp, the circuit power is:

P(W) = I(A) * U(V) = 3 Amp * 240V = 720 Watts

How many Volts are 100 Watts?

Similarly, to find out the voltage of the circuit, we need the circuit's current - for example, if the circuit current is 5 Amp, the circuit voltage is:

U(V) = P(W) / I(A) = 100W / 5A = 20V

How many Amps are 1000 Watts at 240 Volts?

If the circuit features a voltage of 240V and transfers 1000 Watts, then the current is:

I(A) = P(W) / U(V) = 1000 Watts / 240V = 4.166 Amps

How many Watts is a 120V bulb?

Incandescent 120V bulbs are usually between 60-120W, while LED bulbs are 7-18W.

What does the 120V 60Hz mean?

That means that there is 120V between the phase and neutral wire, and the AC current frequency is 60 Hz.

Long Story Short: If You want to convert amps and volts to watts, simply multiply the amps and volts. In order to get amps from watts and volts, divide watts with volts, and in order to get volts from watts and amps, divide watts with amps.

And all these formulas are good for DC electric systems and for AC electric systems where α=0° (cos 0°=1) and effective values are used.