Free online GST calculator for India. Calculate GST, CGST, SGST instantly. Add or remove GST from any amount with all tax slabs (3%, 5%, 12%, 18%, 28%).
Calculate GST
Enter an amount and GST rate to see the calculation.
Understanding GST Calculation
Goods and Services Tax (GST) is a comprehensive indirect tax levied on the supply of goods and services across India. Introduced on July 1, 2017, GST replaced a complex web of central and state taxes including VAT, service tax, excise duty, and octroi with a unified tax system. Understanding how to calculate GST correctly is essential for business owners, accountants, freelancers, and anyone involved in invoicing or financial management.
Ashwheel's free online GST calculator handles both common scenarios: adding GST to a base amount (for creating invoices) and removing GST from a total amount (reverse calculation for finding the taxable value). The tool supports all standard Indian GST slab rates — 3%, 5%, 12%, 18%, and 28% — as well as custom rates. Results are displayed with a full breakdown including base amount, CGST, SGST, total GST, and final total.
How GST Is Calculated
GST calculation depends on whether you are adding tax to a base price or removing it from an inclusive amount. When adding GST, the formula is: GST Amount = Base Amount × (GST Rate / 100). The total becomes Base Amount + GST Amount. When removing GST from an inclusive total, the formula is: Base Amount = Total Amount / (1 + GST Rate / 100). The GST Amount is then Total Amount − Base Amount. In both cases, the total GST is equally divided into CGST (Central GST) and SGST (State GST) for intra-state transactions, or IGST for inter-state transactions.
For example, if a product is priced at ₹1,000 before tax and the GST rate is 18%, the GST amount would be ₹180 (₹90 CGST + ₹90 SGST), making the final price ₹1,180. Conversely, if the total price including GST is ₹1,180, the taxable base amount is ₹1,000, with the same ₹90 CGST and ₹90 SGST split.
Practical Applications
- Invoicing and quotations — accurately calculate the final price including tax for your customers using the Add GST mode.
- Expense reconciliation — extract the taxable value from GST-inclusive receipts and bills using the Remove GST mode.
- Accounting and bookkeeping — maintain accurate records of CGST and SGST components for input tax credit claims and GST returns.
- E-commerce and retail — calculate final product prices including GST for online store listings and point-of-sale transactions.
- Freelancing and consulting — generate professional GST-compliant invoices for your clients with correct tax breakdowns.