ToolForage.
BUSINESS CALCULATOR

GST Calculator

Add GST to a price before tax or extract the included GST from a total. Enter your applicable rate and currency, then choose GST total only or India’s IGST / CGST and SGST presentation.

Calculator

Calculate GST
Labels amounts only; no exchange-rate conversion.
INR
%
Enter your applicable total rate. Shortcuts set arithmetic inputs; they do not classify a supply.
Tax presentation
India-specific components are optional. For other GST systems, choose GST total only and supply the applicable rate.
YOUR RESULTS
Total including GST1,180.00 INR
Taxable base amount
1,000.00 INR
Total GST
180.00 INR
IGST
180.00 INR
CGST
0.00 INR
SGST
0.00 INR

1,000 × 18 ÷ 100 = 180 GST. 1,000 + 180 = 1,180 including GST. Amounts in INR; currency selection changes labels only.

Taxable amount and GST

  • Taxable base amount1,000.00 INR
  • Total GST180.00 INR
Page guide

Taxable value, GST, and the inclusive total

The taxable base and GST add to the inclusive total. In split mode, the total tax is divided equally between CGST and SGST; the rate you enter remains the combined rate. The presentation selector does not determine which treatment legally applies. Currency changes labels, without converting the amount. Inactive Indian components are hidden; the total-only option shows the base and GST without assigning an Indian tax label.

For reversing a percentage change that is not specifically GST, use the Reverse Percentage Calculator and choose whether the original amount was increased or reduced.

The formula

Exclusive: GST = base × rate ÷ 100. Inclusive: base = total ÷ (1 + rate ÷ 100), and GST = total − base.

Reverse GST divides by the tax-inclusive multiplier. Subtracting the entered percentage directly from the total uses the wrong base. Calculations retain full precision and display amounts to currency precision; invoice-level rounding policies can create small differences.

Extracting GST from 1,180

At an illustrative total rate of 18%, an inclusive amount of 1,180 contains a base of 1,000 and GST of 180. An equal CGST and SGST presentation shows 90 in each component, not 180 in each.

How to use this calculator

  1. Choose Add GST to a price or Extract included GST, then select the currency used for your amount.
  2. Enter the price in the mode shown. Results update after valid changes; Calculate also identifies input errors.
  3. Type the applicable total GST rate, or use a 0%, 5%, 18% or 40% arithmetic shortcut. Confirm the rate for the supply yourself.
  4. Select India: IGST, India: CGST + SGST, or GST total only. Check the numerical working and base + tax = total.

Rate selection is separate from arithmetic

GST treatment depends on the supply, classification, place-of-supply rules, exemptions, and other relevant requirements. This calculator applies the rate and presentation you provide. It does not classify goods or services, verify eligibility, or fetch current rate notifications.

For an invoice with several items at different rates, calculate each taxable line or same-rate group separately. A single blended rate may not preserve the item-level tax breakdown. Discounts, cess, freight treatment, reverse charge, and input tax credits can require additional handling outside this price calculation.

GST rate shortcuts and country conventions

The rate shortcuts set 0%, 5%, 18% or 40%; any entered rate from 0% to 100% is supported. India’s 2025 reforms described 5% and 18% main rates with a special 40% rate, but a shortcut does not establish the rate or exemption applying to your transaction. Supply classification and timing still matter.

The IGST / CGST and SGST labels belong to India. For arithmetic in another GST system, choose GST total only and supply the rate you need. This does not calculate Canadian provincial components, Australian taxable-sale eligibility, or any place-of-supply determination.

Assumptions & limitations

What this calculation assumes

  • One entered rate applies to the full taxable base.
  • Split presentation allocates the combined tax equally.
  • Amounts are positive or zero and use one currency.

What to keep in mind

  • No cess, tax credits, returns, exemptions, or compliance decisions are calculated.
  • This is tax arithmetic using user-supplied assumptions, not a tax determination.

Common questions

Is the default rate always applicable?

No. It is a worked-example input. Confirm the rate for your specific supply before using the result.

Does reverse GST mean reverse charge?

No. Here it means extracting included tax from a gross price. Reverse-charge obligations are a separate legal concept and are not assessed by this calculator.

Can I type a rate that is not shown in the shortcuts?

Yes. Enter any applicable rate from 0% to 100%, including decimal rates. A shortcut changes only the rate input, and leaves your amount, currency, mode and presentation intact.

Does selecting CAD or AUD select Canadian or Australian tax rules?

No. Currency controls labels only. Use GST total only for a single entered rate outside India; provincial tax components, eligibility and other country rules are outside this calculation.

Sources & further reading

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