GST Calculator
Estimate GST-inclusive and GST-exclusive invoice values, including CGST/SGST or IGST splits and optional compensation cess.
What this calculator does
This GST calculator helps you estimate tax on India invoices where the amount is either inclusive or exclusive of GST. It also shows the split between CGST and SGST or the IGST amount for the supply type you select.
Inputs explained
- Amount: Enter the invoice value you have in hand.
- Price type: Choose whether the amount already includes GST or GST needs to be added.
- GST rate and supply type: Use the rate and intra-state or inter-state treatment relevant to the transaction.
- Cess: Use this only when compensation cess applies to the goods or transaction.
Inputs
Enter the invoice amount you have.
Results
This calculator is for estimation only. GST rates can change by notification, HSN or SAC classification, and transaction facts.
How GST calculation works
Exclusive amount
If your price is exclusive, GST is added on top:
GST = Base × (Rate ÷ 100) → Total = Base + GST
Example: ₹10,000 at 18% → GST ₹1,800 → Total ₹11,800
Inclusive amount
If your price already includes GST:
Base = Total ÷ (1 + Rate/100) → GST = Total - Base
Example: ₹11,800 at 18% → Base ₹10,000 → GST ₹1,800
Step-by-step example
- Enter an amount such as Rs. 10,000.
- Select whether the amount is GST-exclusive or GST-inclusive.
- Choose the applicable GST rate and whether the supply is intra-state or inter-state.
- Review the taxable value, GST amount, split, and final payable amount in the results panel.
Use cases
- Quick invoice checks before issuing or reviewing a bill
- Comparing inclusive and exclusive pricing for the same transaction
- Checking whether the split should show CGST and SGST or IGST
Assumptions & limitations
- This page is for estimation only and does not classify your product or service under HSN or SAC rules.
- The correct GST rate depends on the item, notification history, and transaction facts.
- Verify the current law, notifications, and invoice facts before relying on the final number.
Sources & references
FAQs
How do I calculate GST when the price is inclusive of tax?
When the price already includes GST, you have to extract the tax portion. A simple working formula is: GST amount = Total × Rate / (100 + Rate). Say your invoice shows Rs 1,180 inclusive of 18% GST. The GST works out to 1,180 × 18/118 = Rs 180, and the base value is Rs 1,000. For 5% it becomes Rate/105, for 12% it's Rate/112, and so on. Always note whether your supplier's quote is inclusive or exclusive before calculating, otherwise input tax credit ends up wrong in GSTR-3B.
What is the difference between CGST, SGST and IGST in a GST bill?
Whenever you sell within the same state, GST splits equally into CGST (Central) and SGST (State). So 18% becomes 9% CGST plus 9% SGST. The moment goods or services move across state lines, only IGST applies at the full rate of 18%. Place of supply decides this, not the billing address. UTGST replaces SGST in Union Territories without legislatures. Many businesses book CGST-SGST for an inter-state sale by mistake and end up with mismatch notices. The HSN/SAC and place-of-supply column in your invoice software must agree.
How do I reverse calculate GST from a total invoice amount?
Reverse calculation comes up daily, especially for retail clients who quote MRP. The math is the same as inclusive-price extraction: Base = Total × 100 / (100 + Rate) and GST = Total minus Base. For an 18% slab on Rs 11,800, base value is 11,800 × 100/118 = Rs 10,000, and tax is Rs 1,800. Useful when the cashier hands you a single-line bill. Don't apply this on combo invoices that mix 5% and 18% items - you have to reverse each line separately, otherwise the tax break-up reported in returns will not match.
Which GST rate should I use for services in India?
The default service rate is 18%, and most professional, IT, consulting, banking and consultancy services fall in that bracket. Some are concessional - transport of goods at 5% without ITC or 12% with ITC, restaurants at 5%, and certain works contracts at 12% or 18%. Healthcare and education are largely exempt. Always confirm using the SAC code on the CBIC rate finder before quoting clients, because rates do shift after Council meetings. If you wrongly charge 12% where 18% is due, the difference still has to be paid out of your pocket later.
How is GST split for intra-state and inter-state sales?
Place of supply is the key. If supplier and place of supply are in the same state, charge CGST + SGST in equal halves. If they differ, charge IGST at the full rate. Example: a Delhi vendor selling to a Delhi buyer at 18% bills 9% CGST + 9% SGST. The same vendor selling to a Mumbai buyer bills 18% IGST. For services, the place of supply rules under Section 12 of the IGST Act decide it, and they don't always follow the buyer's address - especially for events, immovable property and transport.
Can I add compensation cess while calculating GST?
Yes, compensation cess sits over and above the GST rate, and only applies to specific notified items - mostly tobacco products, aerated drinks, coal, motor cars and pan masala. Suppose you sell a car attracting 28% GST + 17% compensation cess. The base price runs through 28% GST first, and the cess is calculated on the same taxable value, not on GST. So Rs 10 lakh becomes Rs 10L + Rs 2.8L GST + Rs 1.7L cess = Rs 14.5L invoice. Cess paid is utilised only against cess output, not against regular GST liability.
Why does my GST amount change after rounding to two decimals?
Rounding differences are normal and the GST law actually allows it. Section 170 of the CGST Act says the tax payable should be rounded to the nearest rupee. When you compute 18% on Rs 99.50, you get Rs 17.91. On a multi-line invoice, line-wise rounding versus invoice-level rounding can throw small mismatches of one paisa to a couple of rupees. Pick one method - Invoice-level rounding is often preferable - and stick to it across all invoices and the GSTR-1 upload. Internal consistency matters more than which method you choose.