A percent off calculator answers the three most common discount questions in one place: how much is the sale price after a percentage reduction, how much money do you actually save, and — for reverse situations — what was the original price before the discount was applied? Whether you are checking a shop receipt, comparing deals online, or working out a trade discount on an invoice, the tool gives you an instant answer plus the full arithmetic working so you can verify every step yourself.
How it works
The core idea behind any percentage discount is that you keep a fraction of the price and discard the rest. A 25% reduction means you keep 75%, which is the complement of the discount. The formula is:
Sale price = original price x (1 - discount / 100)
The saving is the part you do not pay:
Saving = original price x (discount / 100)
These two values always sum to the original price, which gives you a built-in check: sale price + saving = original price.
Reverse calculation
Shops sometimes show only the discounted price. If you know the sale price and the percentage that was taken off, you can recover the original with the inverse formula:
Original price = sale price / (1 - discount / 100)
Divide the sale price by the fraction of the price you are actually paying. For a 25% discount you are paying 75% = 0.75, so original = sale price / 0.75.
Visual bar diagram
The tool draws a colour-coded bar: the green portion represents the sale price you pay and the red portion represents the saving. The width of each portion is proportional to the discount percentage, giving you an immediate visual sense of how large the reduction is.
Worked example
A jacket has an original price of $120 and is on sale at 25% off.
- Discount amount: $120 x (25 / 100) = $120 x 0.25 = $30
- Sale price: $120 - $30 = $90
Now suppose you see the sale tag showing $90 and a sign saying “25% off” but you want to verify the original price. Switch to reverse mode:
- Fraction you pay: 1 - 25 / 100 = 0.75
- Original price: $90 / 0.75 = $120 (confirmed)
| Original price | Discount | Saving | Sale price |
|---|---|---|---|
| $100 | 10% | $10 | $90 |
| $100 | 25% | $25 | $75 |
| $100 | 50% | $50 | $50 |
| $250 | 30% | $75 | $175 |
| $1,200 | 15% | $180 | $1,020 |
Formula note
The formula sale = original x (1 - p/100) is algebraically equivalent to
sale = original - original x p/100, which is how most people do it manually
(calculate the saving first, then subtract). Both routes give the same answer;
the calculator uses the second form in its working steps so each arithmetic
operation is explicit and easy to follow.
The reverse formula original = sale / (1 - p/100) is simply the forward formula
rearranged by dividing both sides by (1 - p/100). It breaks down only when the
discount is exactly 100% (the denominator becomes zero, meaning the item is free and
there is no original price to recover). The calculator guards against this edge case.
Every calculation runs locally in your browser. No numbers are sent to any server.