How it works
GST is charged on the taxable value of a supply. The calculator takes your amount, the rate and two choices: whether the amount is before or after GST, and whether the buyer is in your state.
- Before GST: tax = amount × rate ÷ 100. Total = amount + tax.
- Including GST: taxable value = amount × 100 ÷ (100 + rate). Tax = amount − taxable value.
- Same state: the tax is split into equal halves, CGST and SGST (UTGST in a union territory without a legislature).
- Another state: the whole tax is IGST.
Worked example
Kaveri Agencies in Mysuru sells hardware worth ₹10,000 (before GST) to a buyer in Bengaluru at 18%.
| Line | Amount |
|---|---|
| Taxable value | ₹10,000.00 |
| CGST at 9% | ₹900.00 |
| SGST at 9% | ₹900.00 |
| Total | ₹11,800.00 |
If the buyer were in Chennai, the same ₹1,800 would be charged as IGST at 18%. Going the other way, ₹11,800 including 18% GST gives back ₹10,000 taxable value.
Notes and edge cases
- The rate depends on the HSN or SAC code, and sometimes on a condition such as “pre-packaged and labelled” or a sale value per piece. Look it up in the HSN and SAC finder.
- Place of supply decides the split, not just the buyer’s address. Bill-to-ship-to sales, events and hotel stays follow their own rules. See the place of supply checker.
- Reverse charge: for some supplies the buyer pays the tax. The rate is the same; who pays changes. See the RCM checker.
- Compensation cess and other levies are not part of this calculator.
