# Discount Calculator - Sale Price, Amount Saved, Original Price and Successive Discounts

Page: https://hirantha.me/tools/discount-calculator
Part of: Hirantha Sandaruwan Lakshan free tools (https://hirantha.me/tools)
Updated: 2026-10-13

Find the sale price and amount saved after a discount, the original price from a sale price, or the combined effect of two or three discounts in a row.

This is a free tool that runs in the browser: open the page to use it. File tools process files on the visitor's own device; files are never uploaded or stored. No account, sign-up, payment or watermark.

Enter a price and a discount percentage to see the sale price and how much you save. Switch to the reverse to find the original price from a sale price, or enter two or three discounts to see the single discount they are really worth. You can add a tax or VAT rate of your own after the discount. Prices are shown in rupees and worked out exactly, and nothing you type leaves your browser.

The saving is the price times the discount as a decimal, and the sale price is the price minus the saving. Rs. 5,000 with 20% off saves 5,000 x 0.20 = Rs. 1,000 and costs Rs. 4,000. The tool rounds the saving to the cent and subtracts it from the price, so the figures on the page always add up.

To go backwards, divide the sale price by what is left to pay. If 20% is taken off, 80% is left, so the original price is the sale price divided by 0.80: Rs. 4,000 / 0.8 = Rs. 5,000. Adding 20% to the sale price gives Rs. 4,800, which is wrong, because the 20% was taken from the original price. A discount of 100% cannot be reversed, because nothing is left to pay.

Two discounts in a row multiply, they do not add. Each discount is taken from the price left by the one before. With a price P, a first discount of a% leaves P x (1 - a/100). A second discount of b% then takes b% of that smaller price and leaves P x (1 - a/100) x (1 - b/100). So 20% then 10% leaves 0.80 x 0.90 = 0.72 of the price, a combined discount of 100% - 72% = 28%, not 30%. In percent the combined discount of two is a + b - (a x b) / 100, here 20 + 10 - 2 = 28. For three discounts multiply all three: 20%, 10% and 5% leave 0.80 x 0.90 x 0.95 = 0.684, a combined discount of 31.6%. Multiplication does not depend on order, so the order does not change the result. The tool shows the price after each step and compares the answer with simply adding the percentages.

Tax is optional and starts blank. If you type a rate, it is worked out on the price after the discount, rounded to the cent, and added to give a total. The tool does not know whether tax applies to your purchase or what the rate is, so type the rate shown on your receipt or published by the tax authority. A shop may apply tax and discounts in a different order, so check your receipt.

Two discounts in a row are worth less than their sum (price of Rs. 1,000):
| First discount | Second discount | Sum of the two | Real combined discount | Price after both |
| --- | --- | --- | --- | --- |
| 10% | 10% | 20% | 19% | Rs. 810.00 |
| 20% | 10% | 30% | 28% | Rs. 720.00 |
| 20% | 20% | 40% | 36% | Rs. 640.00 |
| 25% | 25% | 50% | 43.75% | Rs. 562.50 |
| 30% | 20% | 50% | 44% | Rs. 560.00 |
| 50% | 20% | 70% | 60% | Rs. 400.00 |
| 50% | 50% | 100% | 75% | Rs. 250.00 |
| 70% | 30% | 100% | 79% | Rs. 210.00 |

Q: How do I calculate a discount?
A: Multiply the price by the discount percentage divided by 100, and subtract the result from the price. For Rs. 5,000 with 20% off: 5,000 x 0.20 = 1,000, and 5,000 - 1,000 = Rs. 4,000. In one step, multiply the price by 0.80.

Q: How do I find the original price from the sale price?
A: Divide the sale price by 1 minus the discount as a decimal. If a sale price is Rs. 4,000 after 20% off, the original was 4,000 / 0.80 = Rs. 5,000. Do not add 20% to the sale price: that gives Rs. 4,800.

Q: Is 20% off and then 10% off the same as 30% off?
A: No. The second discount is taken from the already reduced price, so the two together equal 28%, not 30%. On Rs. 1,000 that is Rs. 720 instead of Rs. 700. The more discounts you stack, the bigger the gap from the sum.

Q: Does the order of successive discounts matter?
A: No. The final price is the original price multiplied by (1 - each discount as a decimal), and multiplication does not depend on order. 20% then 10% and 10% then 20% both leave 72% of the price. The price after the first step is different, but the final price is the same.

Q: How do I add tax after a discount?
A: Work out the discounted price first, then multiply it by the tax rate and add the result. With a rate of 10% (an example), Rs. 4,000 gives Rs. 400 of tax and a total of Rs. 4,400. Type the rate that applies to your purchase into the optional tax box; the tool does not know current rates.

Q: How do I find the discount percentage from two prices?
A: Divide the amount saved by the original price and multiply by 100. From Rs. 5,000 down to Rs. 4,000 the saving is Rs. 1,000, and 1,000 / 5,000 = 20%. The percentage change calculator does this for you.

Q: How does the tool round?
A: Prices are limited to 2 decimal places. The discount amount (and the tax, if you add one) is worked out exactly and rounded to the nearest cent, with halves going up, then the figures are added or subtracted. For several discounts the final price is rounded once at the end.

Q: Is anything I type sent to a server?
A: No. The sums run in your browser and nothing is stored or sent anywhere.

Sources: Percentage - Wikipedia, section Compounding percentages (after changes of x percent and then y percent the final amount is p(1 + 0.01x)(1 + 0.01y), and changes can be applied in any order; a discount is a change of minus a percent), checked 2026-10-13 (https://en.wikipedia.org/wiki/Percentage); Repeated Percentage Change - MME, GCSE maths revision (the overall change is found by multiplying the multipliers: 10% up then 30% down is 1.1 x 0.7 = 0.77), checked 2026-10-13 (https://mmerevise.co.uk/gcse-maths-revision/edexcel-igcse/repeated-percentage-change/); Percentage - Maths is Fun (percent of a number, worked examples), checked 2026-10-13 (https://www.mathsisfun.com/percentage.html)

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