Percent Off Calculator
Calculate the final price after any discount. Supports single discounts, stackable (two sequential) discounts, and working backwards to find the original price from a sale price.
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How It Works
Multiply the original price by (1 minus the decimal form of the discount). This gives the final price. The amount saved is simply original minus final. Used for any straightforward percentage off situation.
Final = Price × (1 − Discount% / 100)$120 × (1 − 0.25) = $120 × 0.75 = $90The dollar savings equals the original price multiplied by the discount percentage as a decimal. This is the number stores display in the "You save $X" line at checkout.
Saved = Price × (Discount% / 100)$120 × 0.25 = $30 savedSequential discounts multiply, they do not add. A 20% off tag, then a 15% coupon means the coupon applies to the already-reduced price. The effective total discount is always less than the sum of the two percentages.
Final = Price × (1−d1/100) × (1−d2/100)$279 × 0.80 × 0.85 = $189.72 (not 35% off)The effective discount of stacked discounts is: 1 − (1−d1/100) × (1−d2/100). A 20% + 15% stack gives an effective 32% discount, not 35%. Always compare effective discounts when shopping.
Effective% = (1 − (1−d1/100)(1−d2/100)) × 10020% + 15% → 1 − (0.80 × 0.85) = 32%If you know the sale price and the discount percentage, you can work backwards to the original. Divide the sale price by (1 minus the discount as a decimal). Useful for finding original prices from receipts or verifying discounts.
Original = Sale Price ÷ (1 − Discount% / 100)$85 ÷ (1 − 0.15) = $85 ÷ 0.85 = $100A TV listed at $800 has a 30% store discount. You also have a 10% loyalty coupon. Step 1: $800 × 0.70 = $560. Step 2: $560 × 0.90 = $504. You save $296, an effective 37% off — not 40%.
$800 × 0.70 × 0.90 = $504Effective discount: 37%, not 40%Quick Reference
Common discount calculations — verify instantly above.
Single
25% off $120
$90 (save $30)
Single
30% off $150
$105 (save $45)
Single
50% off $200
$100 (save $100)
Single
10% off $49.99
$44.99 (save $5)
Stackable
20% + 15% on $279
$189.72 (32% eff.)
Stackable
30% + 10% on $100
$63 (37% eff.)
Reverse
$85 after 15% off
$100 original
Reverse
$60 after 25% off
$80 original
Tips & Shortcuts
To quickly estimate 20% off: find 10% (move decimal left) and double it. $75: 10% = $7.50, ×2 = $15 off, final = $60.
Stackable discounts always result in less total savings than adding the percentages. 20% + 10% stacked = 28% off, not 30%.
For a 50% discount, the item is half price. For 33.33% off, multiply by 2/3. For 25% off, multiply by 3/4.
To verify a sale price on a receipt: multiply the original by (1 − discount%). If the numbers do not match, check the cashier applied the right base price.
Always compare effective discounts when stacking. A 30% + 10% stack (37% effective) beats two separate 20% discounts stacked (36% effective).
When finding the original price from a sale, divide by the complement: 15% off → divide by 0.85. 30% off → divide by 0.70.
Common Mistakes
Adding stackable discounts: 20% + 15% = 35% off
Stackable discounts multiply. Use: 1 − (0.80 × 0.85) = 32% effective discount, not 35%.
Thinking 50% off then 50% off is free
$100 × 0.50 × 0.50 = $25. Two 50% discounts = 75% off total, not 100%.
Dividing by the discount instead of (1 − discount) to find original
To find original from sale price: divide by the complement. $85 after 15% off → $85 ÷ 0.85 = $100.
Applying the second coupon to the original price instead of sale price
In stackable discounts, each subsequent discount applies to the price after previous discounts are applied.
Confusing the dollar amount saved with the percent saved
$50 off a $200 item is 25% off. $50 off a $500 item is only 10% off. Always compare percentages, not dollar amounts.
Not checking if a "sale price" actually beats buying elsewhere without a discount
A 20% off sale at a store that marked up 40% is still more expensive than the regular price elsewhere.
Frequently Asked Questions
Final Price = Original × (1 − Discount% / 100). Amount Saved = Original × Discount% / 100. Example: $120 at 25% off → $120 × 0.75 = $90 final, $30 saved.
No. Stackable discounts multiply: $100 × 0.80 = $80, then $80 × 0.80 = $64. Effective discount is 36%, not 40%.
Original = Sale Price ÷ (1 − Discount%). If you paid $85 after 15% off: $85 ÷ 0.85 = $100 original price.
A second percentage off applied to the already-reduced price. A store gives 20% off, then you have a coupon for another 15% — that 15% applies to the reduced price, not the original.
Multiply by 0.8. Or: find 10% (move decimal left one place) and double it. $45 at 20% off: 10% = $4.50, ×2 = $9 off, final = $36.
No. 50% + 50% stacked = 75% off total. $100 × 0.50 = $50, then $50 × 0.50 = $25. You pay $25, not $0.
Original price = Sale price ÷ (1 − discount% / 100). Example: item costs $68 after 15% off. Original = 68 ÷ (1 − 0.15) = 68 ÷ 0.85 = $80. Verify: 15% of $80 = $12, $80 − $12 = $68 ✓. A common mistake is adding the discount back: $68 + 15% of $68 = $78.20 ≠ $80, because 15% of $68 is less than 15% of the original $80.
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