Confused about what the GST is and how it will affect your monthly budget or business? We have an easy solution. Download the GST calculator Indian app to estimate your GST Tax and Cost affection. All you need to do is enter your amount choose what rate of GST Percentage (5%, 12%, 18%, 28%) and GST Add or GST minus. Add GST GST Amount = ( Original Cost * GST% ) / 100 Net Price = Original Cost + GST Amount Remove GST GST Amount = Original Cost - ( Original Cost * ( 100 / ( 100 + GST% ) ) ) Net Price = Original Cost - GST Amount GST is 5%, 12%, 18% and 28%.