How to Use the Discount Calculator
This calculator has three modes to cover every discount scenario you encounter while shopping:
- Final price after X% off — the most common use case. Enter the original price and the discount percentage to find what you actually pay and how much you save.
- What % discount am I getting? — enter the original price and the sale price to calculate the exact discount percentage. Useful for comparing deals across stores or verifying that a "sale" is as good as advertised.
- What was the original price? — work backwards from a final price and a discount percentage to find the original price. Useful when the tag only shows the discounted price.
Common Discount Percentages — What You Actually Pay
| Original Price | 10% Off | 20% Off | 25% Off | 30% Off | 50% Off |
|---|---|---|---|---|---|
| $20 | $18.00 | $16.00 | $15.00 | $14.00 | $10.00 |
| $50 | $45.00 | $40.00 | $37.50 | $35.00 | $25.00 |
| $100 | $90.00 | $80.00 | $75.00 | $70.00 | $50.00 |
| $200 | $180.00 | $160.00 | $150.00 | $140.00 | $100.00 |
| $500 | $450.00 | $400.00 | $375.00 | $350.00 | $250.00 |
How to Calculate a Discount in Your Head
You do not always need a calculator. Here are quick mental math tricks for common discount percentages:
10% Off
Move the decimal point one place to the left. $85 → $8.50. Subtract from the original: $85 − $8.50 = $76.50.
20% Off
Calculate 10% first, then double it. $85 → $8.50 × 2 = $17. Final price: $85 − $17 = $68.
25% Off
Divide by 4. $80 ÷ 4 = $20 off. Final price: $60.
50% Off
Divide by 2. The simplest discount to calculate.
15% Off
Find 10% (move decimal), then add half of that for 5%. $80 → $8 + $4 = $12 off. Final: $68.
Is the Sale Price Really a Good Deal? How to Verify
Retailers sometimes inflate original prices before a sale to make the discount look more impressive than it is. Use the "what % am I getting?" mode to verify. If a store shows an item "originally $200, now $170," the actual discount is only 15% — not as impressive as a headline like "HUGE SALE" suggests.
Price tracking tools like CamelCamelCamel (for Amazon) show price history over time, helping you confirm that the "original price" is genuine and the discount is real. A genuine discount is typically the lowest price the item has been in 90 days.
Stacked Discounts — Do They Add Up?
When you apply two percentage discounts in sequence, they do not simply add together. A 20% off sale plus a 10% off coupon is not 30% off — it is 28% off. Here is why:
This matters most on large purchases. Use the calculator twice — first apply the sale discount to get the sale price, then apply the coupon to that price to find your true final cost.
Sales Tax After a Discount
In most US states, sales tax applies to the final discounted price, not the original price. If you buy a $100 item at 20% off and your state tax rate is 8%:
- Discounted price: $80
- Sales tax: $80 × 8% = $6.40
- Total at register: $86.40
Use our Sales Tax Calculator to add the tax to your discounted price.