Black Friday 2025 Countdown
November 29, 2025
Reverse Percentage Calculator: Find Original Price
Verify Black Friday deals and calculate original prices before discounts
Quick Answer Example
Item costs $80 after 20% discount→ Original Price was $100
→ You saved $20
Interactive Calculator
Verify Black Friday 2025 Deals
Use this calculator to check if Black Friday discounts are real. Here are real-world examples:
4K Smart TV
• Listed at $420 after "30% Black Friday discount"
Original price: $420 ÷ (1 - 0.30) = $420 ÷ 0.70 = $600
✅ Actual savings: $180
Gaming Laptop
• Listed at $800 after "20% off"
Original price: $800 ÷ (1 - 0.20) = $800 ÷ 0.80 = $1,000
✅ Actual savings: $200
Nike Running Shoes
• Listed at $80 after "20% Black Friday sale"
Original price: $80 ÷ (1 - 0.20) = $80 ÷ 0.80 = $100
✅ Actual savings: $20
PlayStation 5 Bundle
• Listed at $425 after "15% discount"
Original price: $425 ÷ (1 - 0.15) = $425 ÷ 0.85 = $500
✅ Actual savings: $75
AirPods Pro
• Listed at $195 after "25% Black Friday deal"
Original price: $195 ÷ (1 - 0.25) = $195 ÷ 0.75 = $260
✅ Actual savings: $65
Spot Fake Discounts
Some retailers inflate the "original price" right before Black Friday. Always compare the calculated original price with historical prices on sites like CamelCamelCamel or Keepa for Amazon products.
How to Calculate Original Price (Step-by-Step)
Method 1: Division Formula (Fastest)
Formula:
Original Price = Final Price ÷ (1 - Discount%)
Example: Item costs $80 after 20% discount
- 1Convert percentage to decimal
20% = 20 ÷ 100 = 0.20
- 2Subtract from 1
1 - 0.20 = 0.80
- 3Divide final price by result
$80 ÷ 0.80 = $100
- ✓The original price was $100
Method 2: Find 1% First (No Calculator Needed)
Mental Math Method
Great for quick calculations without a calculator
Example: Item costs $210 after 30% discount
- 1Determine what percentage the final price represents
100% - 30% = 70%
- 2Find 1%
$210 ÷ 70 = $3
- 3Find 100%
$3 × 100 = $300
- ✓The original price was $300
The Formula Explained
Basic Formula
Original Price = Final Price ÷ (1 - Discount Rate)
Why This Works
• If an item has 20% off, you're paying 80% (100% - 20%)
• Dividing by 0.80 "reverses" the discount to find 100%
• Think of it as: If $80 is 80%, what is 100%?
Quick Reference Table
| Discount | You Pay | Divide By |
|---|---|---|
| 10% off | 90% | 0.90 |
| 20% off | 80% | 0.80 |
| 25% off | 75% | 0.75 |
| 30% off | 70% | 0.70 |
| 40% off | 60% | 0.60 |
| 50% off | 50% | 0.50 |
When to Use This Calculator
Shopping & Black Friday
- • Verify advertised Black Friday discounts are real
- • Compare which store had the better original price
- • Check if "sale prices" are actually discounted
- • Calculate true savings on Cyber Monday deals
Budget Planning
- • Determine how much an item cost before markdown
- • Track price history for price drop alerts
- • Calculate reverse VAT/sales tax
- • Analyze spending patterns over time
Business & Retail
- • Find cost price from sale price
- • Reverse engineer competitor pricing
- • Calculate markup from discounted price
- • Determine profit margins accurately
Education
- • Learn percentage concepts in reverse
- • Practice mathematical problem-solving
- • Understand proportional relationships
- • Master real-world math applications
Frequently Asked Questions
How do I find the original price before a discount?
Divide the final price by (1 minus the discount rate). For example, if an item costs $80 after a 20% discount: $80 ÷ (1 - 0.20) = $80 ÷ 0.80 = $100. The formula reverses the discount calculation to reveal the starting price.
How can I verify Black Friday deals are real?
Use the reverse percentage calculator to find the "original price" claimed in the ad. Then check if that price was actually charged before Black Friday using price tracking tools like CamelCamelCamel or Keepa. If the original price was inflated just before the sale, the deal may be fake. Retailers sometimes raise prices 2-3 weeks before Black Friday to make discounts look bigger.
What's the difference between forward and reverse percentage?
Forward percentage calculates the final price after applying a discount (e.g., 20% off $100 = $80). Reverse percentage works backward to find the original price when you only know the final price and discount percentage ($80 after 20% off = $100 original). Think of it as "undoing" the discount.
Can I use this calculator for percentage increases?
Yes! For increases, use a similar formula. If something is now $120 after a 20% increase, the original was: $120 ÷ (1 + 0.20) = $120 ÷ 1.20 = $100. Just change the minus to a plus in the formula when dealing with increases instead of decreases.
How do stores fake Black Friday discounts?
Some stores raise prices 2-3 weeks before Black Friday, then apply a "discount" that brings it back to the regular price or even higher. This is called "fake discounting" or "price anchoring." Use this calculator to verify the math matches their claims, and always check price history tools to see the actual price trend over time. In some jurisdictions, this practice is illegal.
Is 30% off better than "Buy One Get One 50% Off"?
Use the calculator to compare: 30% off one item saves you 30%. BOGO 50% off means you pay 100% + 50% = 150% for two items, or 75% per item on average, which is a 25% discount. So a straight 30% discount is better than BOGO 50% off if you're buying the same quantity.
How accurate is this calculator for tax calculations?
Very accurate for reverse tax calculations. If you know the final price including tax and the tax rate, you can find the pre-tax price. For example, if something costs $108 with 8% sales tax: $108 ÷ 1.08 = $100 pre-tax price. This is useful for budgeting and expense tracking.
What if I know the discount amount instead of percentage?
If you know the discount amount (e.g., "Save $20"), first calculate the percentage: (Discount Amount ÷ Final Price) × 100. For example, if you save $20 on an $80 item: ($20 ÷ $80) × 100 = 25% discount. Then use that percentage in the reverse calculator to find the original price.
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