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.
What this calculator tells you
Splits the original price into "you pay" and "you save" visually, and warns that adding a percentage back does not undo a discount — a common shopper miscalculation.
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.
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.
Edge cases & caveats
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.
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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