How to Calculate Discount Percentage — 3 Simple Methods With Examples

Knowing how to calculate a discount is one of the most practical everyday math skills. Here are 3 simple methods for sale price, percent off, and reverse calculation — with real examples and a quick reference table.

Discount calculator showing 3 methods to calculate percentage off prices
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3 Types of Discount Calculations

Method 1: Find Sale Price (% Off a Price)

Formula: Sale Price = Original × (1 − Discount% ÷ 100)

Example: 30% off $85 → $85 × 0.70 = $59.50

Mental shortcut: Find 10% (move decimal left one place), then multiply. 30% off $85 → 10% = $8.50, 30% = $25.50, sale price = $59.50.

Method 2: Find What Percent Off (Two Known Prices)

Formula: Percent Off = (Original − Sale) ÷ Original × 100

Example: Original $80, sale price $56 → ($80−$56) ÷ $80 × 100 = 30% off

Method 3: Find Original Price (Reverse Calculation)

Formula: Original = Sale Price ÷ (1 − Discount% ÷ 100)

Example: $63 after 30% off → $63 ÷ 0.70 = $90 original price

Common Discount Quick Reference

10% off $100 = $90
20% off $100 = $80
25% off $100 = $75
30% off $100 = $70
40% off $100 = $60
50% off $100 = $50
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Frequently Asked Questions

25% off $80 = $60. Discount amount = $20 ($80 × 0.25), sale price = $80 − $20 = $60.
For 10%: move decimal left one place. For 20%: double the 10% amount. For 25%: divide by 4. For 50%: divide by 2. These work for round percentages without a calculator.