GST calculator — add it or take it out
Add GST to a base price, or work backwards from a GST-inclusive total to find the taxable value and the tax hiding inside it — with the CGST/SGST or IGST split, compensation cess and the full working. Everything runs in your browser.
| Taxable value | ₹10,000.00 |
| CGST @ 9% | ₹900.00 |
| SGST / UTGST @ 9% | ₹900.00 |
| Invoice total | ₹11,800.00 |
Doing this on every invoice?
iAccounting works the split out for you and posts it — CGST, SGST and IGST to the right ledgers, HSN captured, GSTR-1 ready. Free for your first 500 vouchers, and your books stay on your own computer.
Download free Make a GST invoiceThe rate slabs
Indicative — the rate follows the HSN or SAC code of what you are actually supplying.
| Rate | Typically covers | Split within a state |
|---|---|---|
| Nil | Fresh produce, unbranded grain and flour, milk, most healthcare and education | — |
| 0.25% | Rough and semi-processed diamonds and precious stones | 0.125% + 0.125% |
| 3% | Gold, silver, platinum and jewellery | 1.5% + 1.5% |
| 5% | Packaged essentials, edible oil, coal, economy transport, small restaurants | 2.5% + 2.5% |
| 12% | Processed food, business-class air travel, mid-range hotels, some machinery | 6% + 6% |
| 18% | The default for most goods and nearly all services — the rate you will use most | 9% + 9% |
| 28% | Luxury and sin goods — larger vehicles, tobacco, aerated drinks; cess may apply on top | 14% + 14% |
Taking GST out of a total
The mistake that costs the most.
If ₹1,180 already includes 18% GST, the tax is not 18% of ₹1,180. Divide instead: ₹1,180 × 100 ÷ 118 = ₹1,000 taxable value, so the GST is ₹180. Taking 18% of the total would give ₹212.40 — overstating your output tax by more than 18%.
Taxable value = Total × 100 ÷ (100 + rate)
CGST + SGST, or IGST?
One question decides it: where is the place of supply?
Supplier and place of supply in the same state or union territory — the tax splits equally into CGST and SGST (UTGST in a union territory). In different states — the whole amount is IGST. The total is the same either way; only the split and the ledgers change. Getting it wrong means an amendment in GSTR-1 and a mismatch in your customer's GSTR-2B, so it is worth being sure before you issue.
Rates shown are indicative and grouped for guidance — the applicable rate depends on the exact HSN or SAC classification of the goods or services supplied, and rates are revised by the GST Council from time to time. This calculator does not determine classification, reverse charge liability, place-of-supply rules for specific services, or eligibility for input tax credit. Confirm the rate for your supply on the CBIC rate finder or with your CA.
GST, answered
How do I remove GST from a total?
Divide, don't multiply. Taxable value = total × 100 ÷ (100 + rate). At 18%, ₹1,180 becomes ₹1,000 plus ₹180 tax. Taking 18% of the total instead gives ₹212.40, which is wrong and inflates your output tax.
When is it IGST instead of CGST and SGST?
When the supplier and the place of supply are in different states or union territories. Same state means CGST plus SGST, split equally. The total tax is identical — only the split, and the ledgers you post to, differ.
Is GST charged before or after discount?
On the value after any discount shown on the invoice itself. A post-sale discount reduces the taxable value only if it was agreed beforehand, is linked to specific invoices, and the buyer reverses the matching input tax credit.
What is compensation cess?
An extra levy on a small set of 28%-slab goods — tobacco, aerated drinks, coal and larger motor vehicles. It is charged on the taxable value, not on the GST, and is accounted for separately from CGST, SGST and IGST.
Do I charge GST if I'm not registered?
No. Only a registered person may collect GST and issue a tax invoice. Registration is generally required above ₹40 lakh turnover for goods or ₹20 lakh for services, with lower thresholds in special category states, and immediately for inter-state supply of goods and most e-commerce sellers.
Does this send my figures anywhere?
No. The calculation is plain JavaScript running in your own browser. Nothing is uploaded, logged or stored — disconnect from the internet and it still works.
GST that files itself
Invoicing, GSTR-1, 2B reconciliation and an AI accountant that drafts the entries. Free for your first 500 vouchers, and your data never leaves your computer.