GST calculator
Start with a quotation or price before tax. Add your chosen GST rate to see the tax components and final amount payable.
Calculate your GST
Enter an amount in rupees, with up to two decimal places.
Choose a shortcut or enter a custom rate. Confirm the rate for your supply.
Total including GST
₹11,800.00- Amount before GST
- ₹10,000.00
- Total GST (18%)
- ₹1,800.00
- CGST (9%)
- ₹900.00
- SGST (9%)
- ₹900.00
GST is added to the amount you entered.
Rounded to two decimals. A one-paise split adjustment may be applied so the displayed components add up.
How to use the GST calculator
1. Enter your amount
Use the price before tax when adding GST, or the final billed amount when removing GST. Enter numbers without currency symbols or commas. The calculator accepts rupees and paise.
2. Choose the rate
Select a rate shortcut or enter your own percentage. The buttons are calculation presets, not a current rate schedule or a recommendation for a product. Use the rate applicable to the transaction you are reviewing.
3. Read the breakdown
Review the base amount, total GST and final amount. Choose the tax-component display that fits your transaction. Switching the breakdown changes the labels and split, not the total GST.
Build a tax-inclusive quotation
Add GST to a base price
Use this when a quotation lists a price before tax. Multiply the base price by the rate divided by 100, then add the tax to the base price.
GST = Base × Rate ÷ 100
Total = Base + GST
For example, a ₹5,000 before-tax quotation at an illustrative 18% rate gives ₹900 GST and a ₹5,900 final price.
Remove GST from a total
Use this when GST is already included in a billed price. Divide the total by one plus the rate divided by 100. The difference between that base and the total is GST.
Base = Total × 100 ÷ (100 + Rate)
GST = Total − Base
An ₹11,800 inclusive amount at 18% gives a ₹10,000 base and ₹1,800 GST. Simply subtracting 18% from the total would give the wrong base.
Use the result for the right purpose
This tool performs percentage calculations on one amount at one rate. It can help compare quotations, estimate a tax-inclusive selling price or check the arithmetic on an invoice. For items taxed at different rates, calculate each group separately rather than applying one percentage to the entire invoice.
The calculator does not determine product classification, place of supply, exemptions, input tax credit eligibility or registration requirements. It does not include cess, interest, penalties or special valuation rules. Rate shortcuts are not an exhaustive list. Check applicable notifications through the GST Council and confirm transaction-specific treatment with your adviser where needed.
Results are rounded to two decimal places. Your accounting system may use a different line-level or invoice-level rounding policy. A minor difference should be reviewed against the actual invoice rather than treated automatically as an error.
GST calculator questions
What is an inclusive amount?
It is a price that already contains GST. Select Remove GST to separate the base and tax without increasing the total entered.
Can I enter a different GST rate?
Yes. Type a custom percentage in the rate field, with up to two decimal places. The tool calculates that percentage but does not confirm whether it is legally applicable.
How does the component split work?
The CGST + SGST and CGST + UTGST views divide the tax between two components. The IGST view shows the tax as one component. Select the appropriate view; the calculator does not infer it from an address or GSTIN.
Does the calculator store my amounts?
No. Calculations happen in your browser. This tool does not send entered amounts to the GST lookup API or save them as a calculation history.
What happens at a zero rate?
The tax amount is zero and the base equals the total. This is a mathematical result, not a determination that a particular supply is exempt or zero-rated.
Can I also check a supplier’s GSTIN?
Yes. Use our GST number search to review available registration details and filing records. For help interpreting those records, visit the GST search help page.