GST Calculator
Add or remove GST from any amount and see the CGST, SGST and IGST split instantly.
The amount entered is before GST. We add GST on top.
Inter-state supply? The full 18% applies as a single IGST of ₹0.00.
How to use this GST calculator
- Enter the amount you want to calculate GST on.
- Choose a GST rate — tap a preset or type your own.
- Pick Add GST if your amount is before tax, or Remove GST if it already includes tax.
- Read the base amount, the CGST/SGST split and the total instantly.
How GST is calculated
The maths is simple:
- Adding GST: GST amount = Amount × GST rate ÷ 100. Total = Amount + GST.
- Removing GST: Base amount = Amount ÷ (1 + GST rate ÷ 100). GST = Amount − Base.
CGST, SGST and IGST
For a supply within the same state, GST is split equally into CGST (Central GST) and SGST (State GST) — so 18% becomes 9% + 9%. For a supply between different states, the whole amount is charged as a single IGST (Integrated GST) instead. The total tax is the same either way.
GST rate slabs in India
GST is charged at different rate slabs depending on the goods or service — commonly 5%, 12%, 18% and 28%, with special rates for a few categories. Rates are revised by the GST Council from time to time, so always confirm the current rate notified for your specific item.
From calculator to compliance
A calculator is handy for a quick check — but on a real invoice you want GST, HSN codes and the CGST/SGST/IGST split applied automatically, every time. That is what Booksmor does. Start a 30-day free trial and stop calculating GST by hand.
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