Steps for Calculating GST using GST Calculator:

• Enter Product Price of Item i.e. Exclusive GST
  OR
  Enter Final Price of Item i.e. Inclusive GST
• Manage the rate according to your product you can refer Table from Information page.

That's all your GST is calculated.
Now if your sale is Interstate then Note down the value of IGST or if it is Intrastate then note down values of CGST and SGST/UTGST.
For definition of Intrastate and Interstate you can refer Information Page.

Formulae for GST Calculation:

Anyone can calculate GST easily with the help of the following formula:
Where GST is excluded: GST Amount = (Value of supply x GST%)/100 Price to be charged = Value of supply + GST Amount
Where GST is included in the value of supply: GST Amount = Value of supply – [Value of supply x {100/(100+GST%)}]