How to convert Watts to
Amps or Amps to Watts
Basics
You cannot convert watts to amps,
since watts are power and amps are coulombs per second (like converting gallons
to miles). HOWEVER, if you have at least least two of the following three:
amps, volts or watts then the missing one can be calculated. Since watts
are amps multiplied by volts, there is a simple relationship between them.
However, In some engineering
disciplines the volts are more or less fixed, for example in house wiring,
automotive wiring, or telephone wiring. In these limited fields technicians
often have charts that relate amps to watts and this has caused some confusion.
What these charts should be titled is "conversion of amps to watts at a fixed
voltage of 110 volts" or "conversion of watts to amps at 13.8 volts," etc.
Some tidbits of information that
you might need a refresher on: To convert mA to A (milliamps to amps)
1000mA = 1A to convert µA to A (microamps to amps) 1000,000 µA =
1A To converter µA to mA (microamps to milliamps) 1000µA = 1mA
To convert mW to W (milliwatts to watts) 1000mW = 1W To converter
µW to W (microwatts to watts) 1,000,000 µW =
1W 
The Following Equations can be used to convert
between amps, volts, and watts.
Converting
Watts to Amps
The conversion of Watts to Amps at fixed
voltage is governed by the equation Amps = Watts/Volts
For example 12
watts/12 volts = 1 amp Converting Amps to Watts
The conversion of
Amps to Watts at fixed voltage is governed by the equation Watts = Amps x
Volts
For example 1 amp * 110 volts = 110 watts
Converting Watts to Volts
The conversion of Watts to Volts at fixed amperage is governed
by the equation Volts = Watts/Amps
For example 100 watts/10 amps = 10
volts
Converting Volts to
Watts
The conversion of Volts to Watts at fixed amperage is
governed by the equation Watts = Amps x Volts
For example 1.5 amps * 12
volts = 18 watts
Converting
Volts to Amps at fixed wattage
The conversion of Volts to
Amps if the wattage is known is governed by the equations Amps =
Watts/Volts
For example 120 watts/110 volts = 1.09 amps
Converting Amps to Volts at fixed
wattage
The conversion of Amps to Volts if the wattage is
know is governed by the equation Volts = Watts/Amps
For Example, 48
watts / 12 Amps = 4 Volts
Converting Volts to Amps at a fixed resistance
If you know the volts and the load of the resistance the amps are found
by Ohm's law: Amps = Volts / Resistance
Converting Amps to
Volts at fixed resistance
If you know the amps and the
resistance Ohm's law becomes Volts = Amps * Resistance
Explanation
Amps are how many electrons flow past
a certain point per second. It is equal to one coulomb of charge per second, or
6.24 x 10^18 electrons per second. Volts is a measure of how much force that
each electron is under, which we call "potential". Power (watts) is volts times
amps. A few electrons under a lot of potential can supply a lot of power, or a
lot of electrons at a low potential can supply the same power. Think of water
in a hose. A gallon a minute (think amps) just dribbles out if it is under low
pressure (think low voltage). But if you restrict the end of the hose, letting
the pressure build up, the water can have more power (like watts), even though
it is still only one gallon a minute. In fact the power can grow enormous as
the pressure builds, to the point that a water knife can cut a sheet of glass.
In the same manner as the voltage is increased a small amount of current can
turn into a lot of watts.
This is also why increasing the volts does
not necessarily increase the available power. Power is amps times volts, so if
you double the volts you halve the amps unless something in your circuit
actually creates power, such as a battery, solar panel or nuclear power plant.
