Content

• To step
• Method 1 of 3: Converting watts to amperes at a fixed voltage
• Method 2 of 3: Calculate amps using the wattage and DC voltage
• Method 3 of 3: Calculating amps using the wattage and single phase AC current
• Tips
• Warnings
• Necessities

While it is not possible to "convert" a wattage to "amperes", it is possible to calculate this using the ratio of amperes, watts, and voltage. This relationship will be different for different types of systems, such as AC or DC power supply, but will always be the same within a certain type of circuit. If you are working with a fixed voltage circuit, it is common practice to draw graphs showing the relationship between watts and amps for quick reference.

To step

Method 1 of 3: Converting watts to amperes at a fixed voltage

1. Find a watt-to-amp table. For specialized applications, such as wiring in a house or in a car, there are specific voltage ratings. Since these values ​​are always the same, it is possible to construct a graph linking the value of a motherboard to an amperage. These graphs are based on the equations linking wattage to ampere (amperes) and voltage in a circuit. If you plan to use this type of table, you can find it online. Make sure you use a table with the correct fixed voltage.
   • For example, a home usually uses 120V AC (alternating current) and a car generally uses 12V DC (direct current).
   • You can also use an online amperage calculator to make it even easier.
2. Look for the power (in watts) you want to convert. Once you find your chart, look for the value you need. These types of charts usually have multiple rows and columns. There will be a column named "Power" or "Watt." Start from there and find the exact power of the circuit you are dealing with.
3. Find the corresponding amperage (in amperes). When you have found the wattage in the power column, follow the "Current" or "Amps" column in the same row. There may be several columns in the table, so make sure you read the column titles carefully and choose the correct value. Once you locate the amp column, double check the value to make sure it is in the same row as your wattage.

Method 2 of 3: Calculate amps using the wattage and DC voltage

1. Find the circuit's power. Looks for a label on the track you are working with. Power is measured in watts. This value measures the amount of energy used or created in a specific amount of time. For example 1 Watt = 1 Joule / 1 second. This value is necessary for calculating the amperage, measured in amperes (or indicated by the symbol A).
2. Find the voltage (the voltage or V). The voltage is the electrical potential of a circuit and should also be listed on a label along with the power rating. This arises because one side of the circuit contains more electrons than the other. This creates an electric field (the voltage) between the two points. This voltage creates a current through the circuit in an attempt to discharge the voltage (equalizing the charge on both sides). You need to know the voltage to calculate the amperage (or amperes).
3. Draw up the equation. In a DC circuit, the comparison is not very complicated. Watts equals amps times volts. Therefore, you can calculate the number of amps by dividing the wattage by the voltage.
   • Ampere = Watt / Volt
4. Solve for the amperage. Once you've set up the equation, you can calculate the ampere. Do the division to get the number of amps. Check your units to make sure you end up with coulomb per second. 1 Ampere = 1 Coulomb / second.
   • A coulomb is the SI unit of electric charge and is defined as the amount of charge moved in one second by a constant current of one amp.

Method 3 of 3: Calculating amps using the wattage and single phase AC current

1. Know what the power factor is. Power factor in a circuit is the ratio of true power to apparent power delivered to the system. Apparent power is always greater than or equal to true power, so the power factor will have values ​​from 0 to 1. Look for the power factor on the circuit's label or schematic.
2. Use the one-phase equation. The equation for single phase alternating current covering amperes, voltage, and wattage is similar to the equation used for direct current. The difference is the use of the power factor.
   • Ampere = Watt / (PF x Volt) where the power factor (PF) is a value without a unit.
3. Solve for the amperage. Once you have entered the values ​​for watts, volts, and power factor, you can easily solve the equation for amps. You should now use this to calculate the units in coulomb per second. If not, you are using the equation incorrectly and have to try again.
   • The solution for a three-phase voltage has more variables than one phase. You have to decide whether to use line to line or line to neutral voltage, for calculating amps at three phases.

Tips

• Use a calculator.
• Understand that you are calculating amps with the number of watts and volts. You cannot "convert" watts to amps because they measure completely different things.

Warnings

• If you plan to work with electrical circuits, take all necessary precautions.

Necessities

• Calculator