How a discount calculator works
A discount is just a slice taken off a starting price. Whether you are checking a shop’s “25% off” sticker or trying to see how steep a clearance markdown really is, the arithmetic comes down to two small formulas. This calculator handles both directions for you and formats the money with your chosen currency, but it is worth knowing the maths so you can sanity-check any deal in your head.
The two formulas
If you know the original price and the percentage off, the sale price and saving are:
- Sale price:
sale = price × (1 − discount ÷ 100) - Amount saved:
saved = price × (discount ÷ 100)
If instead you know the original and the final sale price, the percentage off is:
- Discount %:
discount = (1 − sale ÷ price) × 100
A worked example
Suppose a pair of headphones is listed at $80 with a 25% off
banner. Plug that into the first formula: 80 × (1 − 25 ÷ 100) = 80 × 0.75 = $60.
The amount you save is 80 × 0.25 = $20. Now flip it around — you spot the same
headphones elsewhere for $60 down from $80 and want the
percentage: (1 − 60 ÷ 80) × 100 = (1 − 0.75) × 100 = 25%. Both views agree, which
is exactly the cross-check this tool gives you.
Common discounts at a glance
| Discount | You pay (per $100) | You save (per $100) |
|---|---|---|
| 10% off | $90.00 | $10.00 |
| 15% off | $85.00 | $15.00 |
| 25% off | $75.00 | $25.00 |
| 33% off | $67.00 | $33.00 |
| 50% off | $50.00 | $50.00 |
| 70% off | $30.00 | $70.00 |
Two directions
Start from a percentage to find the price, or from two prices to find the percentage — switch with one tap.
Clean currency
Results are formatted with your browser’s Intl number formatter, so symbols and separators match your currency.
Pre-tax clarity
The maths stays on the listed price so it works anywhere; add your local sales tax or VAT to the result if needed.