The three questions a discount page answers
The price-after-discount mode is the shop-window arithmetic: an MRP is known, a discount is advertised, and the reader wants the till price. The mode takes one discount, or two discounts stacked in succession, and it adds GST on top as an option.
The discount-from-MRP-and-sale-price mode runs backwards. The sticker says the price has been dropped from the MRP to a sale price; the reader wants to know what percentage that works out to. One division and a conversion to per cent.
The original-price-from-sale-and-discount mode is the verification: a sale price and a stated discount are given, and the question is whether the MRP that is being claimed is consistent. Divide the sale price by one minus the discount, written as a decimal, and the original price falls out.
Why twenty then ten is not thirty
Two discounts stacked in succession multiply. The first discount is applied to the MRP; the second is applied to what remains, not to the MRP again. Twenty per cent off ₹1,000 leaves ₹800. Ten per cent off that ₹800 is ₹80, so the price goes down to ₹720. The total saving is ₹280 against the MRP, and the effective discount is 28 per cent, not 30 per cent.
Written as a formula: final price equals MRP times (1 minus the first discount) times (1 minus the second discount). Any number of discounts chains the same way. The order does not matter for the arithmetic; the first and second slots in this calculator are only for labelling, and the final price is the same if you swap them.
The current GST slabs after 22 September 2025
India moved to a two-plus-two slab GST structure on 22 September 2025, under the 56th GST Council meeting. The rates on most goods are 0, 5, 18 and 40 per cent. The 12 per cent slab has been removed and most of what sat there moved to 5 or 18 per cent. The 28 per cent slab has been restructured: most items moved to 18 per cent, and sin and luxury items moved to 40 per cent. Individual term life and individual health insurance went to nil GST under the same change.
The GST selector on this page lists these four slabs and nothing else, so a reader cannot accidentally apply a rate that no longer exists in 2025-26. Current gold, silver and rough-diamond rates sit outside these four and are not covered here; for a full GST view across input credits, see the GST calculator.
Trade discount before GST, cash discount after
A trade discount shown on the face of the invoice reduces the taxable value of the supply, so GST is charged on the already discounted amount. Two per cent off a ₹10,000 item with 18 per cent GST is tax on ₹9,800, not on ₹10,000. That is the layout this page follows when the discount runs before the GST selector.
A cash discount given after the invoice is different. Under the GST law, a post-supply discount reduces GST only when it is linked to a pre-agreed contract and the recipient has reversed any input tax credit tied to it; otherwise the GST on the invoice stands, and only the price in the ledger is adjusted. The GST calculator covers that post-supply path. This page does not model the post-supply case because the arithmetic needs the invoice reference and the credit reversal; use the GST calculator and your accountant for that.
Worked example you can check
MRP ₹1,000. First discount 20 per cent. Second discount 10 per cent. GST 18 per cent.
| Step | Working | Amount |
|---|---|---|
| MRP | ₹1,000.00 | |
| After first discount | ₹1,000 x (1 - 0.20) | ₹800.00 |
| After second discount | ₹800 x (1 - 0.10) | ₹720.00 |
| Saving against MRP | ₹1,000 - ₹720 | ₹280.00 |
| Effective discount | ₹280 divided by ₹1,000 | 28 per cent |
| GST at 18 per cent | ₹720 x 0.18 | ₹129.60 |
| Till amount | ₹720 + ₹129.60 | ₹849.60 |
A single 28 per cent discount on the same MRP gives the same ₹720 sale price, as the table on the page shows in other combinations as well. A 25 per cent plus 5 per cent stack, by contrast, lands at ₹712.50, an effective 28.75 per cent, because the second discount is applied on a larger residual.
What this calculator leaves out
- Coupons, bank cashback and card-linked offers. These are applied on different bases, often capped, and sometimes paid by the bank rather than taken off the price; this page keeps to the price shown.
- Post-supply credit notes with GST reversal. The ledger paths are specific and bank reconciliation matters; the GST calculator and an accountant handle those.
- Currency conversions. If the MRP is in another currency, convert before the discount step.
- Quantity discounts that change the per-unit price only above a threshold. The arithmetic on this page is a percentage, not a quantity curve.
- Round-off and rounding to a till multiple. Shops often round down to the nearest rupee or ten rupees at the till; this page prints the arithmetic figure.
Who this calculator is meant to help
A shopper checks a shop-window claim before the bill. A small business owner sets a sale and needs to know what headline discount lands at the price the margin allows. An accountant working on invoice formats checks how the GST on an invoice changes with a trade discount shown on the face of the bill. A commerce student verifies a textbook sum on successive discounts.
Frequently asked questions
Why is a 20 per cent then 10 per cent discount not a 30 per cent discount?
Because the second discount is applied to the price after the first, not to the MRP. On ₹1,000, 20 per cent off is ₹800; 10 per cent off ₹800 is ₹720. Total saving is ₹280 or 28 per cent. The order of the two discounts does not change the final price.
How is the effective discount calculated?
Effective discount is the saving against the MRP expressed as a percentage of the MRP. It equals MRP minus sale price, divided by MRP, multiplied by 100. For two stacked discounts d1 and d2, the effective discount is also given by one minus (1 - d1) times (1 - d2), written as decimals.
Which GST rates does the page support?
0, 5, 18 and 40 per cent. These are the rates in force after 22 September 2025, following the 56th GST Council meeting. The 12 per cent slab was removed and the 28 per cent slab was restructured, with most of its items moving to 18 per cent and sin and luxury items moving to 40 per cent.
Does a trade discount on the invoice reduce the GST amount?
Yes, when the discount is shown on the face of the invoice and is given at or before the time of supply. The taxable value for GST is the discounted amount, not the MRP. A post-supply discount reduces GST only in specific cases (pre-agreed contract, input tax credit reversed by the recipient); otherwise the GST on the invoice stands.
How do I get the original price from a sale price and a discount?
Divide the sale price by one minus the discount, written as a decimal. For a sale price of ₹720 after a 28 per cent discount, the MRP is ₹720 divided by 0.72, which is ₹1,000. The orig mode on this page does this arithmetic.
What is the difference between MRP and the sale price?
MRP is the maximum retail price printed on the pack, inclusive of all taxes in India under the Legal Metrology (Packaged Commodities) Rules 2011. The sale price is what the shop actually charges, usually lower than the MRP, and also inclusive of taxes. A discount is the gap between the two.
Does the page handle a cashback that is credited to the card later?
No. A cashback after the sale is settled by the bank or the card network and sits in the customer's statement, not on the shop's invoice. Treat the price on this page as the amount paid at the till, and record the cashback separately in your personal ledger.
Courses that teach the subject behind the discount calculator
Advance Tally Prime Accounting Software Training Certificate Course
An online certificate course in advanced Tally Prime for accounting and finance management.
₹2,500 + 18% GST
Certified GST Professional Course
A certified GST training programme on filing, returns, invoicing and compliance.
₹7,500 + 18% GST
Diploma in Business Accounting and Taxation
Business accounting and taxation online, including Tally, GST filing and tax compliance.
₹15,000 + 18% GST
