Working out a discount — or the price after one — is one of the most common everyday percentage calculations. Here’s the formula, worked examples, and a quick reference table for common discount percentages.
Discount Percentage Formula
If you know the original price and the sale price, and want the discount percentage:
Discount % = ((Original Price − Sale Price) ÷ Original Price) × 100
Example: an item originally priced $80 is now $60. ((80−60) ÷ 80) × 100 = 25% discount.
How to Calculate the Final Price After a Discount
If you know the original price and the discount percentage, and want the final price:
Final Price = Original Price × (1 − Discount % ÷ 100)
Example: a $120 item with a 30% discount. $120 × (1 − 0.30) = $120 × 0.70 = $84.
How Much You Save
Amount Saved = Original Price × (Discount % ÷ 100)
Example: a $120 item with a 30% discount saves you $120 × 0.30 = $36.
Common Discount Percentage Table
| Original Price | 10% Off | 20% Off | 25% Off | 30% Off | 50% Off |
|---|---|---|---|---|---|
| $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 |
Stacking Multiple Discounts
Discounts applied one after another are not simply added together. Each discount applies to the already-reduced price:
Example: a $100 item with 20% off, then an extra 10% off. First: $100 × 0.80 = $80. Then: $80 × 0.90 = $72 — a combined discount of 28%, not 30%.
Frequently Asked Questions
Q: How do I calculate percent off in my head quickly?
A: For 10% off, move the decimal point one place left. For 50% off, halve the price. Combine these for quick estimates (e.g. 30% off = 10% off × 3, then subtract from the price, or just take 70% of the original).
Q: What’s the difference between “% off” and “% discount”?
A: They mean the same thing — both describe the percentage reduction from the original price.
Q: How do I work out the original price if I only know the sale price and discount %?
A: Original Price = Sale Price ÷ (1 − Discount % ÷ 100). Example: a $70 sale price after a 30% discount means the original price was $70 ÷ 0.70 = $100.
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