Discount Calculator
Apply a percentage discount, an extra fixed amount off, or both, and see the final price alongside the true saving.
How it works
A percentage discount multiplies the price by one minus the discount as a decimal. 30% off is a multiplication by 0.7, and the saving is the difference between the two figures.
Stacked discounts do not add. An extra 20% off an already 30%-reduced price is ×0.7 then ×0.8, which is 0.56 — a 44% total reduction, not 50%. Shops rely on the intuition that says 50%.
Order matters when a fixed amount is involved. Taking a percentage off first and then a flat amount leaves a different total than the reverse, so the tool shows which order it applied.
The formula
Sale price
final = original × (1 − percent ÷ 100)
Saving
saved = original − final
Stacked discounts
final = original × (1 − d1) × (1 − d2)
Reverse
original = final ÷ (1 − percent ÷ 100)
Worked examples
| Scenario | Working | Result |
|---|---|---|
| 80 with 25% off | 80 × 0.75 | 60, saving 20 |
| 30% off then a further 20% | ×0.7 × ×0.8 | 44% off, not 50% |
| Paid 60 after 25% off | 60 ÷ 0.75 | 80 originally |
When you'd use it
- Checking a sale price before you reach the till
- Comparing two offers on the same item
- Seeing what stacked discounts really come to
- Working backwards from a sale price to the original
Common questions
Is 30% off then 20% off the same as 50% off?
No. The second discount applies to the reduced price, so you pay 56% of the original — a 44% saving, six points short of 50%. Two stacked discounts are always worth less than their sum.
How do I find the original price from a sale price?
Divide by one minus the discount. A 60 item after 25% off was 60 ÷ 0.75 = 80. Adding 25% to 60 gives 75, which is wrong.
Which comes first, the percentage or the fixed amount?
It changes the total, so it depends on the shop's terms. Taking the percentage off first and then the voucher usually leaves you paying less. The calculator states the order it used.