How Many Amps is 1500 Watts - Watts to Amps Conversion

calculator w150pxWhen converting watts to amps and amps to watts, it is very important to know the actual relationship between these two values and what they actually represent.

2000 watts portable inverters are commonly used for powering 1500 watts loads and many people wonder how many Amps are those 1500 watts.

Little Bit of Theory - Units and Conversion Formulas

When converting units and their values, it is essential to know what is what - here is a very short list with explanations about the most important units:

- 'I': current, rated in Amps (A),

- 'P': power, rated in Watts (W), horsepower (HP), or VA (Volt-Amps, used in AC systems),

- 'U': voltage, rated in Volts (V),

- 'E': energy, rated in Joules (J), or Wh (Watt-Hours),

- 'T': time, rated in seconds (s), minutes, or sometimes in hours (h).

Note: Effective Power of AC electric systems is expressed in Watts, while Apparent Power if such systems is expressed in VA (Volt-Amps).

The effective power of the AC system is calculated using the formula:

P (W) = I (A) * U (V) * cos α

where α is a phase shift between voltage and current.

Apparent Power of the AC system is calculated using the formula:

P (VA) = I (A) * U (V)

In most situations where portable generators are involved, it is safe to assume that:

α= ~0° → cos α = 1

Just be sure not to forget that assumption, if you have to power high inductive or capacitive load!

In order to convert:

- Amps to Watts: P (W) = I (A) * U (V)

- Watts to Amps: I (A) = P (W) / U (V)

- Volts to Amps: I (A) = P (W) / U (V)

- Watts to Volts: U(V) = P(W) / I(A)

- Amps to Volts: U (V) = P (W) / I (A)

- Volt and Amps to Watts: P (W) = I (A) * U (V)

- Watt-Hours to Amp Hours: E (Wh) = Capacity (Ah) * U(V)

Also, it is sometimes required to express the same units using different ratings, for example, watts to HPs and similar:

- 1 HP = 746 watts

- 1 kW = 1.3404825 HP

- 1 Wh = 3600 J

- 1 kJ = 0.2777 Wh

Watts to Horsepower and Watts to Amps Conversion Chart

The following Watts to Horsepower and Watts/HP to Amps chart lists electric currents (given in Amps) of specific loads, depending on the nominal voltage (it was assumed that α=0°, cos 0°=1) at the given power (power expressed in Watts and HP):

Power (Watts) Power (HP) Current @ Nominal Voltage
12 Volts 24 Volts 36 Volts 120 Volts 230 Volts
250 W 0.335 HP 20.83 A 10.41 A 6.94 A 2.083 A 1.087 A
500 W 0.67 HP 41.67 A 20.83 A 13.89 A 4.167 A 2.174 A
746 W 1 HP 62.16 A 31.08 A 20.72 A 6.216 A 3.243 A
1000 W 1.34 HP 83.33 A 41.66 A 27.78 A 8.333 A 4.238 A
1492 W 2 HP 124.3 A 62.16 A 41.44 A 12.43 A 6.487 A
1500 W 2.0107 HP 125 A 62.5 A 41.66 A 12.5 A 6.521 A
2000 W 2.68 HP 166.6 A 83.3 A 55.5 A 16.66 A 8.695 A
2238 W 3 HP 186.5 A 93.25 A 62.16 A 18.65 A 9.730 A
2984 W 4 HP 248.6 A 124.3 A 82.88 A 24.86 A 12.97 A
3000 W 4.021 HP 250 A 125 A 83.33 A 25 A 13.04 A
3730 W 5 HP 310.8 A 155.4 A 103.6 A 31.08 A 16.21 A
4000 W 5.3619 HP 333.3 A 166.6 A 111.1 A 33.33 A 17.39 A
5000 W 6.70 HP 416.6 A 208.3 A 138.8 A 41.6 A 21.74 A
10000 W 13.40 HP 833.3 A 416.6 A 277.8 A 83.3 A 43.48 A

If you wonder how many Amps is 1500 watts at 120 volts, simply find the row with the power of 1500W (2.0107 HP) and under 120 volts check the current - 12.5 Amps.

For short, if you have a 120V load that is rated at 1500 watts, that load draws/requires 12.5 Amps.