Use this free GST calculator to add or remove GST in seconds. Enter an amount, pick the GST rate, and the tool shows the base value, the GST, and the total, with the CGST, SGST and IGST split worked out for you. Everything runs in your browser, with no signup and nothing uploaded.
How the GST calculator works
There are two everyday questions this GST calculator answers. To add GST, it takes your base amount and adds the tax: GST equals amount times rate, and the total is the amount plus that GST. To remove GST, which is a reverse GST calculation, it treats your figure as GST inclusive and works backwards, so the base equals the total divided by one plus the rate, and the GST is whatever is left.
For example, on a base of 1,000 rupees at 18 percent, the GST is 180 rupees and the total is 1,180 rupees. Start from a GST inclusive 1,180 rupees and the calculator returns the same 1,000 rupee base and 180 rupee GST. The same arithmetic applies to bank fees: from 15 October 2026, a 10,000 rupee UPI payment to a larger merchant carries a 40 rupee UPI MDR, and GST at 18 percent on that fee is 7.20 rupees.
CGST, SGST and IGST explained
Indian GST is split by where the supply happens. For a sale within the same state, called intra-state, the GST is shared equally as CGST and SGST, so 18 percent becomes 9 percent CGST and 9 percent SGST. For a sale between states, called inter-state, the whole amount is charged as IGST. This calculator switches the split automatically when you choose intra-state or inter-state.
GST rates in India and what falls under each
The September 2025 reform changed many goods and service entries, commonly using 5%, 18% and a special 40% rate. Nil/exempt supplies and other specific rates also exist. This calculator performs arithmetic using your chosen rate; it does not determine an HSN/SAC classification, exemption or legal taxable value. Check the applicable notification and supply date.
| Rate | Typical category | Examples |
|---|---|---|
| Nil / exempt where the entry applies | Specified essential goods and qualifying exempt services | Education and healthcare exemptions have defined scope and exclusions; not every service in either industry is exempt. |
| 5% | Everyday items | Hair oil, soap, shampoo and toothpaste, packaged dairy like butter and ghee, common medicines and diagnostic kits |
| 18% | Standard rate | Most goods and services, including small cars, televisions, air conditioners and other electronics, and professional and IT services |
| 40% | Specified goods and services in the notified schedule | Examples include qualifying large cars, certain beverages and specified tobacco/pan-masala products. Bidi is 18% from 1 February 2026; tobacco is not one uniform category. Some products also have special valuation or other levies. |
What changed in GST 2.0
The 40% schedule covers specified entries and effective dates. Tobacco changes were staged separately: the notified February 2026 changes place bidi at 18% and specified tobacco/pan-masala products at 40%. Do not apply a blanket rate to every tobacco item or assume ordinary transaction-value arithmetic captures retail-sale-price rules and other levies.
If you raise or receive supplier bills, our accounts payable template helps you track them, and the TDS rate calculator covers tax deducted at source on the same invoices. Freelancers on presumptive tax can also use the 44ADA presumptive tax calculator.
Automate your GST reconciliation
Working out GST on one amount is the easy part. Reconciling it every month is where the time goes. Our app at app.reconscribe.com handles that for you. It matches your purchase books against your GSTR-2B, flags mismatches and missing invoices, and tracks the input tax credit you can actually claim, including credit that carries forward to later months. The same app also automates accounts payable, reading supplier invoices from your inbox, pulling out the line items and tax, and posting them straight into your accounting system. If you lose hours each month to 2B matching or invoice entry, see what reconscribe can take off your plate.
Frequently Asked Questions
How is GST calculated on an amount?
Multiply the base amount by the GST rate to get the GST, then add it to the base for the total. For 18 percent GST on 1,000 rupees, the GST is 180 rupees and the total is 1,180 rupees.
How do I remove GST from a total?
Divide the GST inclusive total by one plus the rate. For an 18 percent inclusive total of 1,180 rupees, the base is 1,180 divided by 1.18, which is 1,000 rupees, and the GST is 180 rupees.
What is the difference between CGST, SGST and IGST?
CGST and SGST apply together on sales within a state and split the GST equally between the centre and the state. IGST applies on sales between states and is collected as a single amount. The total tax is the same either way.
What are the GST rates in India?
Common rates after the reform are 5%, 18% and 40%, alongside nil/exempt and other specific entries. The actual rate depends on the HSN/SAC description, conditions and date. Enter the legally applicable rate; this tool does not classify the supply.
Need to raise GST-compliant invoices, not just calculate the tax? Try our free GST invoice generator.
The calculator remains an arithmetic aid; special valuation, place-of-supply and other levy rules need separate determination.
Sources: GST Council official December 2025 notification summary; CBIC healthcare clarification; CBIC current tax notifications.