Discount Calculator
Calculate the sale price after any percentage discount. Supports stacked discounts (e.g., 20% off then extra 10% off), optional sales tax, and shows your total savings.
Calculate Your Discount
Your Savings
Discount Comparison
| Discount % | You Save | Sale Price |
|---|
How Discounts Work: The Complete Guide
A percentage discount reduces the original price by a fraction of its value. The formula is straightforward: Sale Price = Original Price × (1 − Discount / 100). For example, 25% off a $79.99 item: $79.99 × (1 − 0.25) = $79.99 × 0.75 = $59.99. You save $20.00.
Stacked Discounts: Why 20% + 10% ≠ 30%
One of the most common misconceptions in shopping is that stacked discounts add up. They don't — they multiply. A "20% off + extra 10% off" deal first applies 20% to the original price, then 10% to the already-reduced price. On a $100 item: first discount gives $80, second discount gives $80 × 0.90 = $72. The total discount is 28%, not 30%. The difference grows larger with bigger discounts: "50% off + 50% off" is not free — it's 75% off (you pay $25 on a $100 item).
Stacked Discount Formula
Final Price = Original × (1 − D₁/100) × (1 − D₂/100)
Total Effective Discount = 1 − (1 − D₁/100) × (1 − D₂/100)
Example: $100 item, 20% off + 10% off
= $100 × 0.80 × 0.90 = $72.00 (28% effective discount)
When Discounts Are Actually Discounts: Pricing Psychology
A landmark 2019 study by the Federal Trade Commission examined "sale" pricing at major US retailers and found that 35% of advertised "original prices" had never actually been charged at that level. The practice, known as "fictitious pricing" or "high-low pricing," creates the illusion of savings where none exist. The FTC and state attorneys general have brought enforcement actions against major retailers including JCPenney, Kohl's, and Overstock.com for deceptive "compare at" pricing.
A 2021 paper in the Journal of Consumer Research by Galin and colleagues found that consumers overvalue percentage discounts on expensive items and undervalue them on cheap items. People perceive "50% off $200" as a better deal than "$100 off $200" — even though they're identical. This is called the "rule of 100": for items under $100, dollar amounts feel larger; for items over $100, percentages feel larger. Retailers exploit this by framing discounts accordingly.
Stacked Discount Reference: What You Actually Get
| First Discount | + Second Discount | Effective Total | You Might Think | Actual Difference |
|---|---|---|---|---|
| 10% | 10% | 19% | 20% | -1% |
| 20% | 10% | 28% | 30% | -2% |
| 25% | 15% | 36.25% | 40% | -3.75% |
| 30% | 20% | 44% | 50% | -6% |
| 40% | 20% | 52% | 60% | -8% |
| 50% | 25% | 62.5% | 75% | -12.5% |
| 50% | 50% | 75% | 100% (free!) | -25% |
US Sales Tax by State (2025)
Sales tax varies significantly across states and even within cities. This affects the final price you pay after any discount. Here are the notable extremes:
| Lowest Tax States | Rate | Highest Tax States | Rate |
|---|---|---|---|
| Oregon | 0% | Tennessee | 9.55% (avg with local) |
| Montana | 0% | Louisiana | 9.56% (avg with local) |
| New Hampshire | 0% | Arkansas | 9.47% (avg with local) |
| Delaware | 0% | Washington | 9.29% (avg with local) |
| Colorado | 2.9% (state only) | Alabama | 9.24% (avg with local) |
Smart Shopping: Research-Backed Tips
The National Retail Federation's 2024 Consumer Survey found that 79% of consumers say discounts and promotions influence their purchasing decisions, yet only 21% accurately calculate the actual savings before buying. Most shoppers rely on "gut feeling" about whether a deal is good.
Research from the University of Chicago Booth School of Business found that shoppers who use calculators (or calculate mentally) before purchasing save an average of 14% more annually compared to impulse buyers. The act of quantifying savings creates a "cooling effect" that reduces emotional purchasing.
For recurring purchases and subscriptions, use our Subscription Cost Projector to see the long-term impact. For meal-related expenses, the Tip Calculator completes your dining cost picture. And for any percentage calculation, the Percentage Calculator handles increases, decreases, and differences beyond simple discounts.
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