Free tool
GST Calculator
Add GST to a base amount, or strip it out of a tax-inclusive total — with the CGST, SGST and IGST split shown for both intra-state and inter-state supply.
Amount before GST
Rates since 22 September 2025. Use Other for older invoices at 12% or 28%.
Result
- Base amount
- ₹0.00
- CGST
- ₹0.00
- SGST
- ₹0.00
- Total GST
- ₹0.00
- Total amount
- ₹0.00
Runs entirely in your browser. Nothing is sent to us or stored.
How GST is calculated
GST is a percentage of the taxable value of a supply. The arithmetic is simple; what trips businesses up is the direction of the calculation and the split between heads.
Adding GST to a base amount
Multiply the base by the rate. A ₹50,000 service at 18% carries ₹9,000 of GST, giving an invoice total of ₹59,000. The formula is:
GST = Base × Rate ÷ 100
Removing GST from an inclusive total
This is the one people get wrong. You cannot simply take 18% off a GST-inclusive figure — that understates the base. Divide instead:
Base = Total ÷ (1 + Rate ÷ 100)
A ₹59,000 inclusive total at 18% divides by 1.18 to give ₹50,000, with ₹9,000 of GST. Taking 18% off ₹59,000 would have given ₹48,380 — a ₹1,620 error on a single invoice.
The rates since GST 2.0
From 22 September 2025 the GST Council cut the structure to two main rates, 5% and 18%, plus 40% for a short list of luxury and sin goods. The 12% and 28% slabs are gone: most 12% items moved to 5%, and most 28% items moved to 18%. Special rates survive for a few categories, such as 3% on gold and jewellery. If your products changed rate, check that your invoicing software, your price lists and any inclusive MRPs changed with them. A stale rate in the item master is the most common source of post-reform GSTR-1 errors.
CGST, SGST and IGST
Where the supply stays within one state, the tax splits evenly between the central and state governments: an 18% supply becomes 9% CGST and 9% SGST. Where the supply crosses state lines, the whole 18% is charged as IGST. The customer pays the same total either way — the split determines which government receives it and how the credit flows.
Where this usually goes wrong in practice
- Reverse calculation on MRP-inclusive sales — retailers quoting inclusive prices and then computing tax as a flat percentage of the total.
- The wrong place of supply — charging CGST/SGST on what is legally an inter-state supply, which then has to be corrected and re-paid.
- Rounding per line instead of per invoice — small differences that compound into GSTR-1 mismatches.
- Post-supply discounts — reducing taxable value for discounts that weren’t agreed in advance and linked to invoices.
Each of these surfaces later as a GSTR-2B mismatch or a notice. If that’s a recurring pattern in your business, our GST and TDS compliance service handles the reconciliation before the return goes out rather than after.
GST calculator — common questions
How do I calculate GST on an amount?
To add GST, multiply the base amount by the rate: ₹10,000 at 18% gives ₹1,800 GST and a total of ₹11,800. To remove GST from a tax-inclusive figure, divide by (1 + rate). ₹11,800 ÷ 1.18 returns the ₹10,000 base.
How do I remove GST from a total (reverse GST)?
Base amount = total ÷ (1 + GST rate). For 18%, divide the inclusive total by 1.18. The GST component is the total minus that base. This calculator does it for you when you choose “Remove GST”.
What is the difference between CGST, SGST and IGST?
For a supply within the same state, GST splits equally into CGST (central) and SGST (state) — 18% becomes 9% + 9%. For a supply between states, the whole amount is charged as IGST instead. The total tax is identical either way; only the split changes.
What are the current GST slabs in India?
Since 22 September 2025 the main rates are 0%, 5%, 18% and 40%. Most goods and services sit at 5% or 18%; 18% is the standard rate for most services. The 40% rate applies to a short list of luxury and sin goods. A few special rates remain, such as 3% on gold and jewellery and 0.25% on rough diamonds. Confirm the rate for your HSN or SAC code before you invoice.
What happened to the 12% and 28% GST slabs?
The GST Council abolished both from 22 September 2025. Almost everything at 12% moved to 5%, with the rest going to 18%. Items at 28% moved to 18%, or to the new 40% rate for luxury and sin goods. Some tobacco products stay at their earlier rates, plus compensation cess, for a transitional period. You still need 12% or 28% to check invoices raised before the change, so the calculator accepts any rate in the Other box.
Is GST calculated on the discounted price?
Yes. GST applies to the transaction value after any discount shown on the face of the invoice. Discounts given after the supply only reduce the taxable value if they were agreed beforehand and are linked to specific invoices.
Serving businesses across India
Filing GST every month?
We handle GSTR-1, GSTR-3B and GSTR-2B reconciliation end to end, with due dates tracked ahead of time rather than chased on the deadline.
Delivered within 24 working hours, or next month is on us. 24 working hours from the moment we have your complete data. The clock runs Monday to Saturday and pauses on Sundays and public holidays. Terms