Watts to Amps (W to A) Conversion Calculator
What Is Amps?
Amps is short for amperes – the S.I unit of electrical current. It measures electrical current, which is the rate of flow of electrical charge/electrons through a circuit per unit time. Essentially, amps represents the amount of electrons moving through a circuit per second.
What Is Watts?
Watts is the S.I unit of power. When it comes to electricity, it represents the amount of electrical energy consumed or generated by electrical devices per unit time. In other words, watts is a measure of how fast electrical appliances consume or generate electrical energy.
Why Convert Watts to Amps?
To Know If Your Wiring Is Good Enough
Doing a watts-amps conversion helps give an idea of the “electron traffic” to expect in the circuit. This knowledge becomes useful when trying to ensure your wiring can withstand the incoming electric current.
By comparing the input electric current of your solar panel (or any other energy source) with the maximum ampacity of your wires, you can tell if the wires would work or if you’d have to replace them.
Using wires whose ampacity falls below the input current might cause a fire.
While it is vital to match the output voltage of your solar panel to your charge controller and battery, it is also important to match amperage.
Amperage could affect the charging rate of your battery when it falls below what is expected. Generally, with lower amperage, charging is slower. Then again, excessive electric current could destroy the battery.
So, by converting watts to amps, you can ensure faster charging rate. A watts-to-amps conversion also helps avoid potential damage to your battery.
To Avoid Overloading an Outlet
Depending on their current rating, outlets can support different levels of electrical loads. Knowing the total amperage of all the loads you intend to connect to an outlet can keep you from overloading the outlet.
For instance, if you intend to connect a 10 amps washing machine and a 9 amps vacuum cleaner to a 15-amp outlet, you will overload it. The total load of (10 + 9 amps) 19 amps is way beyond the 15 amps threshold of the outlet.
The amperage rating of your home appliances may not be stated clearly. However, the wattage would be provided. So, with that, you can convert watts to amps. Then you can calculate the total amperage and verify that you won’t overload the outlet.
How to Convert Watts to Amps
Watts to Amps Formula
To calculate watts, we multiply electric current (a) with voltage (v). Meaning:
watts = amps x volts
So, to calculate amps, all we have to do is divide watts by volts:
amps = watts ÷ volts
The watts to amps formula above applies to direct current (DC) on any watts to amps calculator. You can also use it for rough estimates involving alternating current (AC). But if you want more accurate watts to amps AC conversion, you must use power factor.
What Is Power Factor?
Power factor (pf) is simply the ratio of the real power (rp) to the apparent power (ap) in a circuit. It is a measure of efficiency – how many watts remains in the circuit following losses, and it is typically less than one.
For a one-phase/single-phase system:
pf = real power ÷ apparent power
three-phase system (line to line voltage):
pf = real power ÷ (apparent power x √3)
three-phase system (line to neutral voltage):
pf = rp ÷ (ap x 3)
Going by the formulas above, watts to amps conversion for a one-phase system:
amps = rp ÷ (volts x pf)
3-phase line to line voltage:
amps = rp ÷ (volts x pf x √3)
3-phase line to neutral voltage:
amps = rp ÷ (volts x pf x 3)
Watts to Amps Conversion Examples
AC Voltage Examples
Say we have a 120 volts single-phase outlet supplying 1000 watts with a pf of 0.8, how many amps is in that outlet?
watts to amps calculation for the outlet = 1000 ÷ (120 x 0.8) = 10.42 amps
The same conversion for a 3-phase outlet with a line-line voltage of 240 volts supplying 2400 watts with a 0.83 pf, the result would be:
= 2400 ÷ (240 x √3 x 0.83) = 6.96 amps
DC Voltage Examples
What if we have a solar generator producing 30 watts through its 12 volts outlet, and we want to convert watts to amps to get its amperage?
Direct current watts to amps calculations are straightforward:
= 30 ÷ 12 = 2.5 amps
Let’s assume we have a 24 volts solar battery that generates up to 100 watts and we want to calculate amps.
= 100 ÷ 24 = 4.2 amps
AC and DC Power Systems
As hinted above, there are two types of power systems, depending on the direction of electron flow.
In direct current systems (DC), electron typically flows in one direction, and there’s rarely any change in direction. Solar power and batteries are two of the commonest sources of DC.
Unlike DC power systems, electron flow in alternating current systems changes direction periodically.
Alternating current is the prime choice for mains electrical supply. In other words, the electricity that you get from the outlets in your home is alternating current.
The appliances that run on electricity from your outlets are designed to use AC. So, to use them with your solar panels or batteries, you need an inverter to convert AC to DC. This is the primary function of an inverter in a solar system.
Why Is Alternating Current Used in Grid Electricity Instead of DC?
Over long distances, alternating current is easier to transmit than direct current. Also, direct current is prone to significant losses over long distances but alternating current isn’t.
Why Is AC Not Stored in Batteries Like DC?
Since AC changes direction periodically, reversing its polarity, the positive and negative half cycles of the battery you attempt to store it in will eventually neutralize each other. In the end, no energy would be stored in battery.
With time, supplying AC to a battery may even damage the battery. These are the reasons batteries only use DC.
Watts to Amps Quick Conversion Chart
The chart below shows quick w to a conversions at common AC voltages (120 volts and 240 volts):
Amperage at 120 volts (amps)
Amperage at 240 volts (amps)
The following chart shows quick w to a conversions at common DC voltages (12 volts, 24 volts, and 48 volts):
Amperage at 12 volts (amps)
Amperage at 24 volts (amps)
Aperage at 48 volts (amps)
How to Convert Watts to Volts (W to V)
Earlier, we mentioned how to calculate watts by multiplying amps and volts. Well, by adjusting that same formula, we can convert watts to volts the same way we convert watts to amps. We can also convert amps or volts to watts. But the scope of this article will focus on converting watts to other electrical quantities.
Before we go into the watts to volts conversion formula, let’s define volts.
What Is Volts?
Volts is the S.I unit of electromotive force. As the word electromotive force hints, volts is a measure of the force required to move electrons around a closed circuit.
Watts to Volts Formula
The formula is similar to what is used in watts to amps calculator. However, in the case of watts to volts, instead of dividing the wattage of the appliance by voltage, we divide by amperage (electric current).
So, to calculate volts from watts, we use this formula:
volts = watts ÷ amps
Watts to Volts Conversion Examples
A battery gives off 200 watts while having an electric current of 8.3 amps. What is the voltage of the battery?
= 200 ÷ 8.3 = 24.09 volts
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