Tools To India

GST Calculator

Enter an amount and a rate to add GST to it, or to work out how much GST is already inside a price that includes it.

Last updated

Rate structure effective from 2025-09-22
What do you want to do?

Choose "remove" when the amount you have already includes GST.

₹10K

The result updates as you type. Nothing you enter is saved, sent to a server or shared.

Total price including GST

₹11,800

18% GST on an exclusive amount

Price split

  • Base amount: ₹10,000
  • GST: ₹1,800
Base amount (before GST)
₹10,000
GST amount
₹1,800
Total (including GST)
₹11,800

Intra-state supply

CGST @ 9%
₹900
SGST @ 9%
₹900
  • For a supply within one state, GST is split equally between the centre (CGST) and the state (SGST).
  • The correct rate depends on the HSN or SAC code of the specific goods or service. Check the CBIC rate notification for anything you are unsure about.

How this calculator works

GST is a destination-based tax charged at each stage of supply, with credit for the tax already paid on inputs. For anyone quoting or checking a price, only two questions matter: what is the rate, and does the number in front of me already include it?

Adding GST is straightforward — multiply by the rate and add. Removing it is where mistakes happen. To extract GST from an inclusive price you divide by (1 + rate ÷ 100); you do not simply take the rate percent of the inclusive figure. On a ₹1,180 inclusive price at 18%, the GST is ₹180, not ₹212.40.

The rate structure was rationalised with effect from 22 September 2025. The 12% and 28% slabs were largely removed, with items redistributed into 5% and 18%, and a 40% rate introduced for demerit and luxury goods. Special rates of 0.25% and 3% continue for precious stones and for gold and silver.

Within a state, GST splits equally into CGST for the centre and SGST for the state. Across states, a single IGST is charged instead. The total is the same either way — only the split changes.

The formula

Adding GST to an exclusive price

GST = amount × rate ÷ 100 Total = amount + GST

Removing GST from an inclusive price

Base = inclusive amount ÷ (1 + rate ÷ 100) GST = inclusive amount − base

This is the step people most often get wrong. Taking 18% of an inclusive price overstates the tax, because that 18% is calculated on a figure that already contains it.

Worked example: ₹1,180 inclusive of 18% GST

An invoice shows ₹1,180 including GST at 18%, for a supply within the same state.

Step-by-step calculation for the worked example
Inclusive amount₹1,180
Divide by 1.18 to get the base₹1,000
GST = ₹1,180 − ₹1,000₹180
CGST @ 9%₹90
SGST @ 9%₹90
Wrong method: 18% of ₹1,180₹212.40

The GST is ₹180, not ₹212.40. The wrong method overstates the tax by ₹32.40 on this invoice — a 18% error that compounds quickly across a month of transactions.

Things worth knowing

  • The rate depends on the specific HSN code for goods or SAC code for services. Similar-sounding products can attract different rates, so check the CBIC notification rather than assuming.
  • Composition scheme dealers pay a flat percentage of turnover and cannot charge GST separately on their invoices or pass on input credit. Their prices are not GST-exclusive in the usual sense.
  • Some supplies fall under reverse charge, where the recipient pays the GST rather than the supplier. This calculator computes the amount; who pays it depends on the nature of the supply.
  • Exports and supplies to special economic zones are zero-rated, which is not the same as exempt: zero-rated supplies still allow input tax credit, exempt ones do not.
  • This tool calculates tax on a single amount. It does not compute input tax credit, net liability, or anything that belongs on a GST return.

Frequently asked questions

How do I find the GST inside a price that already includes it?
Divide the inclusive amount by (1 + rate ÷ 100) to get the base, then subtract that from the inclusive amount. For 18%, divide by 1.18. Taking 18% of the inclusive figure directly gives a number that is too high.
What are the current GST slabs?
Following the rationalisation effective 22 September 2025, the main rates are 5% and 18%, with 0% for nil-rated items and 40% for demerit and luxury goods. Special rates of 0.25% and 3% apply to rough precious stones and to gold and silver. The earlier 12% and 28% slabs were largely folded into 5% and 18%.
What is the difference between CGST, SGST and IGST?
They are the same tax collected differently. A supply within one state is split equally into CGST for the central government and SGST for the state. A supply between two states carries a single IGST at the full rate, collected by the centre and apportioned to the destination state. The amount you pay is identical.
Do I have to register for GST?
Registration depends on your aggregate turnover, the state you operate in, and the nature of your supplies — thresholds differ for goods and services and for special category states. Certain suppliers, such as those making inter-state taxable supplies or selling through e-commerce operators, must register regardless of turnover. Check the current thresholds on the GST portal.

Sources

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