Determining amounts of liquids is important especially in farming and industry. It is also needed in calculating budget and income figures such as new purchases. In farming it may apply to milk production and usage or to fuels used by the farm. In industry these figures may be calculated in the production of food products. The calculation procedure is the same whether it’s hundreds of gallons or only a few.

Things You Will Need
  • Calculator

  • Pencil

  • Paper

Write down the gross beginning number of gallons of the product that was available. If the product is gas, for example, your last purchase invoice will show the number of gallons purchased. If it’s a 100-gallon tank, assume that on that day it contained 100 gallons.

Calculate the number of gallons used.

Subtract the number of gallons used from the gross number of gallons in the beginning. The result will be the net gallons available for use. If your records show that 20 gallons was used, then you know that there are 80 gallons left.