Business Finance
Discount Calculator
Find the price after a discount, check the percentage saved, or work backward to the original price. Add a second successive discount to see what you actually pay and why the rates do not simply add together.
Your price breakdown
One currency · before taxAn example, not your result
20% + 10% off saves 28%, not 30%.
See the price after each step, the amount saved and the effective discount.
The method
Calculate percent off without losing track of the price
For a sale price, multiply the original price by one minus the discount rate. Each additional discount applies to the price left after the previous step. To check a discount, divide the amount saved by the original price. To work backward, divide the sale price by one minus the discount rate. This calculator uses exact integer cents and rounds each discount step to the nearest cent, with halfway values rounded up. The effective percentage is calculated from the final cent-rounded savings.
Example 1
20% off, then another 10% off
The first discount saves 20 on a price of 100, leaving 80. The second saves 10% of 80, or 8—not another 10. You pay 72 and save 28 in total. The effective discount is 28%. Adding the rates would incorrectly suggest a price of 70.
- Original
- 100.00
- After 20% off
- 80.00
- After extra 10% off
- 72.00
- Total saved
- 28.00 · 28%
Example 2
Check a sale price or work backward
A price reduced from 100 to 75 saves 25, which is 25% of the original. If you instead know only that 75 is the price after 25% off, divide 75 by 0.75 to recover 100 before rounding.
- Sale price
- 75.00
- Discount
- 25%
- Remaining share
- 75%
- Original
- 100.00
Example 3
Why a cent can change the answer
25% off 99.99 gives 74.9925 before rounding, so the payable amount here is 74.99. At the smallest scale, half of 0.01 is 0.005; our half-up convention rounds that to 0.01. Retailers may round a complete basket instead of each step, so compare their actual receipt.
- Original
- 99.99
- Discount
- 25%
- Before rounding
- 74.9925
- Rounded price
- 74.99
Before you calculate
Assumptions & limits
- All amounts use the same currency and a two-decimal minor unit. Currency conversion and currencies with a different minor-unit convention are outside this model.
- Amounts are limited to 999,999,999.99. Original price must be positive when calculating savings. Percentages accept 0–100 with up to two decimal places; original-price mode requires a discount below 100%.
- Each percentage-discount step rounds to cents, halfway up. The summary percentage rounds to two decimals. Coupon eligibility, minimum purchase, maximum savings, fixed-amount coupons, cashback, shipping and tax are not included.
- A reverse calculation is an estimate. Rounding can allow multiple original prices to produce the same sale price. The result shows what happens when the discount is reapplied to the estimate.
- Calculations stay in this tab. Inputs are not saved or included in URLs or analytics. Copying the breakdown is an explicit action you control.
Keep in mind
Common mix-ups
Is 20% off plus 10% off the same as 30% off?
No. If the discounts apply successively, the second rate is applied to the reduced price. Before cent rounding, the remaining share is 0.80 × 0.90 = 0.72, so the effective saving is 28%.
How do I find the original price from a sale price?
Divide the sale price by the share remaining after the discount. For 25% off, that share is 0.75. A 100% discount leaves no information about the original price, so it cannot be reversed.
Does a 50% discount followed by a 50% increase restore the price?
No. Starting at 100, the discount leaves 50. A 50% increase on 50 adds 25, giving 75. The original price and discounted price are different percentage bases.
Do these results include sales tax?
No. Coupon tax treatment depends on the offer and applicable rules. This page isolates the discount arithmetic. Use the actual retailer checkout for a payable tax-inclusive total.
Sources & calculation notes
Educational reference for single and successive percentage discounts. The cent-rounding convention and worked receipts on this page are explicitly defined by BiznTools.
Calculation and input rules checked: . Engineering validation; no professional accounting review is claimed.