Discount Calculator
A "30% off" sticker tells you the discount but not what you will actually pay. This calculator turns any percentage off into the two numbers that matter at the till: the final price and the amount you save. Enter the original price and the discount, and it does the rest.
- Final price
- You save
- Original price
- $100.00
- You save
- $20.00
- Final price
- $80.00
A 20% discount on 100 saves you 20.00, bringing the price down to 80.00.
How it works
A percentage discount is taken off the original price. To find the saving, convert the discount to a decimal (divide by 100) and multiply by the price. Subtract that saving from the original price and you have the final, discounted price.
There is a neat shortcut: instead of calculating the saving and subtracting, you can multiply the price by one minus the discount fraction. A 20% discount means you pay 80% of the price, so final price = original × 0.80. This is faster mentally and is exactly what the calculator does under the hood.
The saving and the final price always add back up to the original price, which is a quick way to check the result. The donut chart splits the original price into what you pay and what you save, so the size of the deal is obvious at a glance.
amount saved = original price × (discount% ÷ 100); final price = original price − amount saved. Equivalently, final price = original price × (1 − discount% ÷ 100).
Worked example
A 100 item at 20% off saves you 100 × 0.20 = 20, so the final price is 80. Using the shortcut, 100 × (1 − 0.20) = 100 × 0.80 = 80 — the same answer in one step.
Things to watch out for
A 100% discount makes the item free; a 0% discount leaves the price unchanged. Discounts above 100% are not meaningful for a single markdown and are blocked here. Note that a percentage off is not the same as a percentage added back: taking 20% off 100 gives 80, but then adding 20% to 80 only returns 96, not 100 — because the 20% is calculated on different base amounts. For two stacked discounts, use the double discount calculator instead.
Frequently asked questions
How do I calculate a percentage discount?+
Multiply the original price by the discount percentage divided by 100 to get the saving, then subtract it from the price. Or multiply the price by (1 − discount ÷ 100) directly to get the final price in one step.
What does "20% off" actually save me?+
It saves you 20% of the original price. On a 100 item that is 20, leaving a final price of 80. The higher the original price, the larger the saving for the same percentage.
Why doesn't adding the percentage back give the original price?+
Because the percentage is applied to different base amounts. Taking 20% off 100 removes 20; adding 20% to the resulting 80 only adds 16. The two percentages are calculated on different starting numbers, so they do not cancel out.
How do I handle two discounts at once?+
Stacked discounts do not simply add together. A 20% then 10% discount is not 30% off. Use the double discount calculator, which applies them one after the other and shows the true effective rate.
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Disclaimer: This calculator is for educational and informational purposes only and provides estimates, not financial advice. Interest rates, taxes, fees, and local rules vary and change over time. Confirm figures with a qualified professional before making any financial decision.
Last reviewed: 2026-06-22