Discount calculator
This discount calculator shows the sale price and the amount you save. The second mode works backwards: give it the original and the final price, and it returns the percentage off.
An extra field for a second discount checks offers like “20% off plus another 10% with a code” — those discounts never simply add up.
Price after discount
3,992
You save
998
Discount is 20%
Discount formulas
- Sale price = price × (1 − percent ÷ 100). $49.90 at 20% off becomes $39.92.
- Savings = original price − sale price. In the example that is $9.98.
- Percent off = (original − final) ÷ original × 100.
- Original price = final price ÷ (1 − percent ÷ 100).
Why stacked discounts are smaller than they look
A second discount applies to the already reduced price, so 20% and 10% give 28%, not 30%. An item at $100 drops to $80 after the first cut and to $72 after the second, a total saving of $28.
This matters with promo codes and loyalty cards: the real saving is almost always less than the sum of the advertised percentages.
Discount table
| Discount | $20 item | $100 item | $500 item |
|---|---|---|---|
| 5% | $19.00 | $95.00 | $475.00 |
| 10% | $18.00 | $90.00 | $450.00 |
| 15% | $17.00 | $85.00 | $425.00 |
| 20% | $16.00 | $80.00 | $400.00 |
| 30% | $14.00 | $70.00 | $350.00 |
| 50% | $10.00 | $50.00 | $250.00 |
| 70% | $6.00 | $30.00 | $150.00 |
Doing it in your head
- 10% is the price with the last digit removed: $24.90 gives $2.49.
- 20% is 10% twice: $4.98 on the same price.
- 5% is half of 10%: $1.25.
- 15% = 10% + 5%. Combining these parts covers most discounts.
- 25% is a quarter of the price and 50% is half.
Frequently asked questions
How do I calculate a discount?
Multiply the price by the percentage and divide by 100 to get the discount amount, then subtract it from the price.
How do I find the percentage off from two prices?
Divide the price difference by the original price and multiply by 100. From $50 down to $40 is 20% off.
Is 20% off plus 10% off the same as 30% off?
No, it works out to 28%. The second discount is taken from the already reduced price.
How do I find the original price before a discount?
Divide the final price by (1 − discount ÷ 100). A $32 item after 20% off started at $40.
Does it include sales tax or cashback?
No, it works with the item price only. Tax and cashback are applied separately at checkout.
Updated: 2026-08-09