GST Calculator

Add or remove GST and split the tax into indicative intra-state or inter-state components.

Adjust your plan

Enter an exact value or use a slider. Your result updates instantly.

Formula, example and assumptions
Invoice total₹1,180.00
Indian rupees

Your result

Local calculation
Invoice total₹1,180.00

The invoice total includes GST. Choose whether your entered amount is before tax or already includes it; the supply type determines whether GST is split into CGST and SGST or shown as IGST.

Amount type
Before GST — add tax
GST rate
18%
Supply type
Intra-state (CGST + SGST)
See how this is calculated

Invoice composition

Taxable value85%
Total GST15%

Result breakdown

Taxable value
₹1,000.00
Total GST
₹180.00
CGST
₹90.00
SGST
₹90.00
IGST
₹0.00
Check the inputs and method

These are your current inputs, not the worked example further down the page.

Amount
₹1,000
Amount type
Before GST — add tax
GST rate
18%
Supply type
Intra-state (CGST + SGST)

Method

For rate r = GST percent/100: add mode gives gross = amount × (1+r) and GST = amount × r. Extract mode gives taxable value = amount/(1+r) and GST = amount − taxable value. Intra-state mode divides GST equally into CGST and SGST; inter-state mode puts the full GST in IGST.

Read the worked example and assumptions

How this calculation works

Add GST to a price quoted before tax or extract it from an invoice total that already includes tax. Choose the supply split only after determining the applicable tax treatment: the calculator performs the arithmetic but does not classify the goods, services or place of supply.

For rate r = GST percent/100: add mode gives gross = amount × (1+r) and GST = amount × r. Extract mode gives taxable value = amount/(1+r) and GST = amount − taxable value. Intra-state mode divides GST equally into CGST and SGST; inter-state mode puts the full GST in IGST.

Worked example

This example uses illustrative inputs. Your current result is shown above.

Choose Add GST, ₹1,000 taxable value, 18% GST and intra-state supply. GST is ₹180 and invoice total is ₹1,180, split into ₹90 CGST and ₹90 SGST. Choosing Extract GST with ₹1,180 and the same rate returns ₹1,000 taxable value and ₹180 tax.

Assumptions and limits

  • The selected rate applies to the whole amount; mixed-rate invoice lines need separate calculations.
  • The entered amount already reflects any adjustments to the taxable value.
  • Compensation cess, reverse-charge accounting, input tax credit and classification questions are outside this calculation.

Questions people ask

Why can I not subtract 18% from a GST-inclusive bill?

The 18% was charged on the pre-tax price, not on the final total. Dividing by 1.18 reverses the addition; multiplying the gross total by 18% overstates the embedded tax.

Does selecting a state split establish the place of supply?

No. The intra-state and inter-state choices merely allocate the calculated tax. Place-of-supply rules and any special treatment must be established separately.

Can I calculate GST for several rates at once?

This form applies one rate. Calculate each taxable group separately and reconcile the line amounts and rounding against the invoice.

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