Our GST Reverse Calculator lets you find the original base price from a GST-inclusive amount. If you know the final price (including GST) and the GST rate, this tool instantly shows you the pre-GST price and the exact GST amount paid.
GST Reverse Calculator
GST Reverse Calculation Formula
Base Price = GST-Inclusive Price ÷ (1 + GST Rate/100)
GST Amount = GST-Inclusive Price − Base Price
Example: You paid ₹1,180 including 18% GST.
Base = 1180 ÷ 1.18 = ₹1,000
GST = 1180 − 1000 = ₹180
GST Rates in India (Post GST 2.0, effective 22 September 2025)
| GST Rate | Common Items |
|---|---|
| 0% | UHT milk, paneer, roti/chapati/paratha, fresh vegetables, life-saving drugs, school stationery |
| 5% | Packaged food, most FMCG, gyms/salons/barbers/yoga studios, small cars on EVs, economy flights |
| 18% | Most services, electronics, white goods (AC/TV/dishwasher), cement, small petrol/diesel cars, restaurants, hotels |
| 40% | Luxury cars and SUVs, pan masala, gutkha, chewing tobacco, cigarettes, aerated drinks |
The 12% and 28% slabs no longer exist for most goods. If you are working from an older price list or invoice template, check it against the current rate, since a 12% or 28% figure on anything but a handful of legacy cases is now out of date.
What is GST?
Goods and Services Tax (GST) is India’s unified indirect tax that replaced VAT, Service Tax, Excise Duty, and other levies on 1 July 2017. It is collected at every stage of the supply chain but only the final consumer bears the actual tax burden.
CGST, SGST and IGST — What’s the Difference?
- CGST: Central GST — goes to the central government (half the GST rate)
- SGST: State GST — goes to the state government (half the GST rate)
- IGST: Integrated GST — applies to inter-state transactions, full GST rate
Example: On an 18% GST transaction within Maharashtra, you pay 9% CGST + 9% SGST.
Forward vs Reverse GST Calculation
Two different questions come up constantly in business, and they use opposite formulas.
| Question | Formula | Example at 18% |
|---|---|---|
| I have the base price, what is the GST-inclusive price? | Base x (1 + rate/100) | 1,000 x 1.18 = 1,180 |
| I have the inclusive price, what is the base price? | Inclusive / (1 + rate/100) | 1,180 / 1.18 = 1,000 |
Worked Example: An Invoice With Multiple Items
A retail invoice totalling 5,900 rupees inclusive of GST, where all items are taxed at 18 percent:
- Base price: 5,900 / 1.18 = 5,000
- GST amount: 5,900 – 5,000 = 900
- Split for an intra-state sale: CGST 450, SGST 450
- Split for an inter-state sale: IGST 900
How to Read a GST Invoice
A compliant GST invoice separates several figures that are easy to confuse when reverse-calculating:
- Taxable value is the base price before tax, the number this calculator produces from an inclusive amount.
- CGST and SGST appear as two separate lines for an intra-state sale, each at half the applicable rate.
- IGST appears as a single line, at the full rate, for an inter-state sale.
- Cess, where it applies (mainly on the 40 percent luxury and sin goods slab), is shown separately and is not part of the standard GST rate.
Input Tax Credit: Why the Reverse Calculation Matters for Business
For a GST-registered business, the GST paid on purchases (input tax) can usually be set off against the GST collected on sales (output tax), so only the net amount is paid to the government. Correctly separating the base price from the GST component on every purchase invoice is what makes this claim accurate.
Common GST Calculation Mistakes
- Subtracting the rate instead of dividing. The single most common and most expensive reverse-GST error.
- Using a stale rate. The 12 percent and 28 percent slabs were removed for most goods under GST 2.0, effective 22 September 2025. Any price list still quoting them needs updating.
- Confusing CGST plus SGST with a doubled rate. They are each half of the single applicable rate, not two separate taxes stacked on top of each other.
- Applying IGST logic to an intra-state sale, or vice versa. The split depends on whether buyer and seller are in the same state, not on the transaction value.
Frequently Asked Questions
How do I calculate GST reverse in India?
Divide the GST-inclusive price by (1 + GST rate / 100). For an 18% rate, base price = inclusive price / 1.18. On an invoice of 1,180 rupees at 18%, that gives a base price of 1,000 and GST of 180. Do not subtract the percentage directly from the inclusive price, since that produces the wrong answer.
What is the current GST rate structure in India?
Since GST 2.0 took effect on 22 September 2025, India runs on essentially two main slabs, 5% and 18%, with a separate 40% slab for luxury and sin goods such as tobacco, pan masala and luxury cars. The earlier 12% and 28% slabs were removed for most items, with 12% goods generally moving to 5% and 28% goods generally moving to 18%.
What is the GST on restaurants?
Standard restaurants, including AC restaurants and standalone takeaway, charge 5% GST without input tax credit. Restaurants inside hotels charging room rates above 7,500 rupees a night typically charge 18% GST on food, with ITC available. This treatment has stayed consistent through the GST 2.0 reform.
What is the difference between CGST, SGST and IGST?
CGST and SGST each represent half of the applicable GST rate and apply to sales within the same state, going to the central and state governments respectively. IGST is the full GST rate and applies to inter-state sales, collected by the central government and apportioned to the destination state. All three total the same overall tax rate on the transaction.
How has GST changed under GST 2.0?
Effective 22 September 2025, the four-slab structure of 5%, 12%, 18% and 28% was simplified to primarily two slabs, 5% and 18%. Most 12% items moved to 5% and most 28% items moved to 18%. A new 40% slab was introduced for luxury and sin goods including luxury cars, pan masala and tobacco products, and a range of essentials such as UHT milk and paneer moved to 0%.
Can I claim input tax credit on every purchase?
No. Input tax credit is not available for every category. Restaurant services taxed at 5% are a common example of a supply made without ITC eligibility. Correctly separating the base price from GST on your purchase invoices, using the reverse calculation, is what makes an accurate ITC claim possible where it does apply. Confirm eligibility for your specific category before claiming.
Is this calculator still valid after the GST 2.0 changes?
The reverse-calculation formula itself, dividing the inclusive price by (1 + rate/100), is unaffected by rate changes and works for any GST rate. Just make sure you enter the current rate for your item: 5% or 18% for most goods and services after 22 September 2025, or 40% for luxury and sin goods, rather than an older 12% or 28% figure.