How to Use This GST Calculator
Select Add GST if you have a price before tax and want to find the final price. Select Remove GST if you have a GST-inclusive price and want to extract the base price and the tax component. Enter the amount using the slider or type it in directly, then type the GST rate that applies to your item (or tap a quick button). The calculator updates instantly as you change any value.
GST Formula Explained
Adding GST: Total Price = Base Price × (1 + GST Rate / 100). The GST amount = Base Price × GST Rate / 100.
Removing GST:Base Price = Inclusive Price / (1 + GST Rate / 100). The GST amount = Inclusive Price − Base Price. This is also called "back-calculation" or "GST reverse calculation."
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Frequently Asked Questions
Which GST rate should I use?
Use the rate printed on your invoice or the one your accountant gives you for that item. GST rates differ by item and can change, so this calculator does not list them — type the rate in, or pick one of the quick buttons.
How do I calculate GST on a price?
To add GST: multiply the base price by the GST rate and add it to the base. For example, for ₹1,000 at 18% GST, the tax is ₹180 and the total is ₹1,180. To remove GST from an inclusive price: divide the inclusive amount by (1 + rate/100). For ₹1,180 at 18%, the base price = ₹1,180 ÷ 1.18 = ₹1,000.
What is the difference between CGST, SGST, and IGST?
GST is split into Central GST (CGST) and State GST (SGST) for intra-state transactions — each levied at half the applicable rate. For inter-state transactions, Integrated GST (IGST) is levied at the full rate. For example, an 18% GST on an intra-state sale means 9% CGST + 9% SGST. Our calculator shows the total GST amount; the split depends on whether the transaction is intra-state or inter-state.