Free tool
GST calculator for India: add or remove GST
Enter an amount, pick the rate and say whether GST is already included. See the taxable value, the GST, the CGST and SGST or IGST split and the total, rounded to paise.
Check your item's rate by its HSN code. 12% and 28% apply to invoices before 22 September 2025.
GST at 18%
Total including GST
₹11,800.00
How the GST calculator works
GST to add to an amount before GST
GST = amount × rate ÷ 100
Total including GST
Total = amount + GST
GST inside an amount that includes GST
GST = amount × rate ÷ (100 + rate)
Taxable value from an amount that includes GST
Taxable value = amount − GST
Within your state
CGST = SGST = GST ÷ 2, each at half the rate
To another state
IGST = GST, at the full rate
How to use the GST calculator
The GST calculator adds GST to a price or takes it out of a price that already includes it, in four steps. Every result is rounded to paise.
The results show the taxable value (the price before GST), the GST amount, how it splits into CGST and SGST or IGST, and the total the customer pays.
- Amount: type the rupee amount, such as 12000 for ₹12,000.
- GST rate: choose 0%, 3%, 5%, 18% or 40%, or type a custom rate, such as 0.25% or the 12% on an old bill.
- Amount is: choose Before GST to add GST to a price, or Including GST to take GST out of a price that already contains it.
- Supply type: choose Within my state for CGST and SGST, or To another state for IGST.
How GST is calculated: exclusive and inclusive prices
When your price is before GST (exclusive), GST is the amount multiplied by the rate and divided by 100. At 18%, ₹1,000 carries ₹180 of GST, and the customer pays ₹1,180.
When your price already includes GST (inclusive), you cannot simply take 18% of it. The GST inside is the amount multiplied by the rate and divided by 100 plus the rate. For ₹1,180 at 18%, that is 1,180 × 18 ÷ 118 = ₹180, which leaves a taxable value of ₹1,000. This is what people mean by a reverse GST calculation.
The split depends on where the supply goes. Within your state, half the rate is CGST and half is SGST, or UTGST in a union territory. To another state, the whole rate is IGST. Which one applies is decided by your location and the place of supply.
Worked GST examples
Adding GST within a state. A spice trader in Ahmedabad bills a shop in Vadodara ₹12,000 before GST for goods taxed at 5%. GST is 12,000 × 5 ÷ 100 = ₹600. Both are in Gujarat, so the invoice shows CGST at 2.5% of ₹300 and SGST at 2.5% of ₹300, and the total is ₹12,600.
Removing GST from a counter price. A shop in Pune sells an appliance for ₹3,540 including GST at 18%. The GST inside the price is 3,540 × 18 ÷ 118 = ₹540, so the taxable value is ₹3,000. The receipt shows CGST at 9% of ₹270 and SGST at 9% of ₹270.
Adding GST on an inter-state sale. A Delhi distributor sends goods worth ₹1,25,000 before GST at 18% to a retailer in Jaipur. Rajasthan is another state, so the invoice carries IGST at 18% of ₹22,500, and the total is ₹1,47,500.
Rounding to paise. ₹1,000 including GST at 18% holds 1,000 × 18 ÷ 118 = ₹152.54 of GST. The taxable value is ₹847.46, with CGST and SGST of ₹76.27 each.
GST rates after the September 2025 changes
Since 22 September 2025, most goods and services in India are taxed at one of two main GST rates, 5% or 18%, with a special rate of 40% for a short list of luxury and sin goods. The GST Council recommended this at its 56th meeting on 3 September 2025, and the 12% and 28% slabs were removed for most items. Pan masala and tobacco products moved on a separate, later timeline.
Some special rates remain, such as 3% on gold and 0.25% on rough diamonds, and many essentials are exempt at 0%. Use the custom rate box for any rate that is not a preset.
Invoices dated before 22 September 2025 can correctly show 12% or 28%. When you check an old bill, use the rate printed on it, not today's rate. For anything you bill now, confirm the rate for your item's HSN code on CBIC's GST rates page or the GST portal's HSN search, because the rate follows the exact HSN code and description, not the everyday name of the product.
Common GST calculation mistakes
Most GST errors on small business invoices come from a handful of habits. Check for these before you send a bill.
- Taking 18% of a price that already includes GST. On ₹3,540, that gives ₹637.20 instead of the correct ₹540, and a taxable value ₹97.20 too low.
- Splitting the amount instead of the rate. CGST and SGST are each half the rate, so 18% becomes 9% plus 9%, never 18% plus 18%.
- Charging CGST and SGST on a sale to another state, or IGST on a sale within your state.
- Using an old 12% or 28% rate on a new invoice, or today's rate when you check an old one.
- Guessing the rate from the product's name instead of looking up its HSN code.
- Mixing rounding methods. Round each line's GST to paise, add up the lines, and do it the same way every time, so your invoices and your accountant's figures agree.
When a GST calculator is no longer enough
A calculator is right for one price at a time. Once you bill every day, the GST has to be right on every line of every invoice and added up for your accountant, and a spreadsheet copy of your bills soon falls behind.
managemate, GST billing software for small businesses, does this on the invoice itself. Each product keeps its GST rate and HSN or SAC code, prices can be entered with or without GST included, and CGST and SGST or IGST is chosen from your GSTIN state and the customer's ship-to state. Each tax invoice shows place of supply, HSN codes, a GST summary by rate and the amount in words, and Reports show GST collected on sales, GST paid on purchases and the difference for any period. It does not file GST returns or generate e-invoices or e-way bills, so your accountant still files.
GST calculator: common questions
How do I calculate GST on an amount?
Multiply the amount before GST by the rate and divide by 100. For ₹5,000 at 18%, GST is ₹900 and the total is ₹5,900. Within your state, that ₹900 is shown as ₹450 CGST and ₹450 SGST; on a sale to another state, it is ₹900 IGST.
How do I remove GST from a price that includes GST?
Multiply the price by the rate and divide by 100 plus the rate: that is the GST inside it. For ₹1,050 at 5%, GST is 1,050 × 5 ÷ 105 = ₹50, and the price before GST is ₹1,000. Choose Including GST in the calculator and it does this for you.
What are the GST rates in India now?
Since 22 September 2025, most goods and services are taxed at 5% or 18%, with a 40% rate for a short list of luxury and sin goods. Special rates remain, such as 3% on gold and 0.25% on rough diamonds, and many essentials are exempt. Check your own item's rate by its HSN code on the CBIC or GST portal.
When do I charge CGST and SGST, and when IGST?
Charge CGST and SGST, each at half the rate, when you and the place of supply are in the same state, and IGST at the full rate when they are in different states. A sale at 18% from Mumbai to Pune is 9% CGST plus 9% SGST; from Mumbai to Bengaluru it is 18% IGST.
Are the 12% and 28% GST rates still used?
For most items, no: the 12% and 28% slabs were removed from 22 September 2025, and those items moved mainly to 5%, 18% or 40%. You will still see 12% and 28% on invoices dated before that day. Enter them as a custom rate in the calculator when you check an old bill.
How do I find the GST rate for my product?
Find your product's HSN code, then look up the rate for that code on CBIC's GST rates page or the GST portal's HSN search. Your supplier's invoice usually shows the HSN code, and your accountant can confirm it. On B2B tax invoices, businesses with turnover up to ₹5 crore in the previous year show at least 4 digits of the code, and larger businesses 6.
Why does my invoice total differ from the calculator by a paisa?
Usually because of rounding. The calculator rounds once, on the amount you enter, while an invoice with several lines rounds the GST on each line and then adds them up. Some businesses also round the invoice total to the nearest rupee. Small differences like this are normal; just use one method consistently.
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