📚 Guide
Discount Calculator Guide – How to Calculate Sale Prices
Learn how to quickly calculate discounts, understand percentage off deals, and never be confused by sale tags again.
The Basic Discount Formula
Calculating a percentage discount is straightforward. The formula has two simple steps:
💰 Savings Amount
Savings = Original Price × (Discount % ÷ 100)
🏷 Final Price
Final Price = Original Price − Savings
Quick Examples
20% Off
$100 item at 20% off
Savings = $100 × 0.20 = $20
Final Price = $80
50% Off
$60 item at 50% off
Savings = $60 × 0.50 = $30
Final Price = $30
75% Off
$200 item at 75% off
Savings = $200 × 0.75 = $150
Final Price = $50
Mental Math Shortcuts
| Discount | Quick Shortcut | Example ($100) |
|---|---|---|
| 10% | Move decimal 1 place left | $100 → $90 |
| 20% | Double the 10% amount | $100 → $80 |
| 25% | Divide by 4, multiply by 3 | $100 → $75 |
| 50% | Divide by 2 | $100 → $50 |
| 75% | Divide by 4 | $100 → $25 |
How to Compare Discounts
Which is better: 30% off or $20 off? It depends on the original price!
For a $50 item:
30% off = $15 saved → $35 final
$20 off = $20 saved → $30 final
🏆 $20 off is better
For a $100 item:
30% off = $30 saved → $70 final
$20 off = $20 saved → $80 final
🏆 30% off is better
💡 Rule of thumb: For items under ~$67, a fixed $20 off beats 30%. Above $67, the percentage wins.
Stacked Discounts: A Common Trap
"Extra 20% off already reduced prices!" Stacked discounts are not additive — 30% + 20% ≠ 50% off.
$100 item with 30% off, then extra 20% off:
Step 1: $100 − 30% = $70
Step 2: $70 − 20% = $56
Total discount = 44%, NOT 50%
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