AAA batteries can be measured using voltage for the most part. They are rated at 1.5 volts each and depending on the battery will depend on how much wattage is produced from those volts. It seems on average that AAA batteries have a measurement of a bit less than 2 watts per battery. This can go up or down, however, based on the amp level that the battery operates at.
Description of a Watt
A watt is a unit of measurement for the output of energy. It is also used in equations for the process of conversion to other energy sources. One watt equals one joule of energy or power second.
Formula For Figuring Wattage from Voltage
In order to accurately figure the wattage of a battery from the voltage of said battery you would also need to know the amps that the battery runs at. You can find this information online or from the manufacturer of the particular battery you are testing or using. Once you have that information the formula is; watts divided by amps equals volts or amps time volts is the total watts.
To accurately asses the question presented you would need to know at least two variables. Once you have two of the variable you can find the third.