Reverse GST calculator
Know the final price but need the amount before tax? Separate a GST-inclusive total into its base price and GST, without changing the amount paid.
Find the price before GST
Start with the final price. We’ll separate the base amount and included tax.
Enter an amount in rupees, with up to two decimal places.
Choose a shortcut or enter a custom rate. Confirm the rate for your supply.
Price before GST
₹10,000.00Original total including GST: ₹11,800.00
- Amount before GST
- ₹10,000.00
- Total GST (18%)
- ₹1,800.00
- CGST (9%)
- ₹900.00
- SGST (9%)
- ₹900.00
GST is extracted from your total; the total stays unchanged.
Rounded to two decimals. A one-paise split adjustment may be applied so the displayed components add up.
From final price to base amount
1. Enter the inclusive total
Use the amount that already contains GST. Enter rupees and up to two decimal places, without commas or currency symbols. Do not use a before-tax quotation here: this calculator assumes tax is already included.
2. Enter the applicable rate
Choose a percentage shortcut or type a custom rate. Use the combined GST rate, not just one component. For example, if a document shows two components of 9% each, enter 18% for the calculation.
3. Review the result
The highlighted figure is the price before GST. The breakdown shows the included tax and its selected components. Changing the component display does not change the base amount or the inclusive total.
The reverse GST formula
Recover the base price
GST is calculated on the base price, so the inclusive total represents the base plus its tax percentage. To undo that addition, divide by the corresponding multiplier.
Base price = Inclusive total × 100 ÷ (100 + GST rate)
Included GST = Inclusive total − Base price
A worked example
Suppose the inclusive total is ₹2,240 and the chosen rate is 12%. Dividing ₹2,240 by 1.12 gives a base of ₹2,000. The difference, ₹240, is the GST included in the price.
In a two-component display, that tax is split into ₹120 and ₹120. In the IGST display, it appears as one ₹240 amount. These figures illustrate the arithmetic, not a rate recommendation.
Useful for prices that already include tax
Compare supplier quotes
Separate tax from an inclusive quotation before comparing it with another supplier’s before-tax price. Check that the products, quantities and other charges are comparable too.
Review invoice arithmetic
Check whether the stated base and tax reconcile with a billed total at a known rate. A mathematical match does not verify the invoice, supplier identity or treatment of the transaction.
Plan an inclusive selling price
Explore how much of a proposed final price is the base and how much is tax. The base is not profit: costs, discounts and other business expenses still need a separate review.
Get a meaningful result
Do not subtract the stated percentage directly from the inclusive total. For example, taking 18% away from ₹118 gives ₹96.76, while reversing an included 18% tax gives a ₹100 base. The percentage applies to the base, not to the tax-inclusive figure.
Use one rate at a time. If an invoice contains items at different rates, separate the corresponding inclusive amounts and calculate each group independently. Do not apply a single rate to a mixed-rate bill or include unrelated charges without checking how they are treated.
The result is rounded to two decimal places, with any one-paise component difference reconciled to the displayed tax. Invoice-level and line-level rounding can differ. This calculator does not include cess, penalties or special valuation adjustments, and it does not select the legally applicable rate. Rate buttons are shortcuts, not a complete current rate schedule.
Reverse GST questions, answered
Can I find the GST rate from the total alone?
No. The same inclusive price can correspond to different base amounts at different rates. Supply the applicable percentage to obtain a meaningful breakdown.
Can I use a decimal rate?
Yes. The rate field accepts up to two decimal places, including values such as 2.5%. It calculates the value entered without deciding whether that rate applies to your transaction.
What if I enter zero?
A zero total gives a zero base and zero tax. At a zero rate, the base equals the inclusive total. Neither result classifies a supply for tax purposes.
Does removing GST change what was paid?
No. It separates an existing total into base and tax. It does not issue a refund, change an invoice or alter any payment.
Are my entries saved?
No calculation history is stored by this tool. The arithmetic runs in your browser without sending your amounts to the GST lookup API. Reset restores the sample amount and rate.
Where can I add GST instead?
Use the GST calculator to add tax to a base amount or switch between both modes. To review a business’s available registration record, use GST number search.