Discounts are everywhere — sales, clearance events, coupon codes, wholesale pricing, and subscription renewals. Knowing how to calculate a discount quickly means you will never overpay, and you will always know whether a deal is actually a deal. This guide covers every discount scenario you will encounter, with formulas, worked examples, and tips for spotting misleading discount claims.
How to Calculate a Discount: The Basic Formula
Discount Amount = Original Price × (Discount % ÷ 100)
Sale Price = Original Price − Discount Amount
Example: A jacket costs $120 and is 35% off. Discount = $120 × 0.35 = $42. Sale price = $120 − $42 = $78.
How to Find the Discount Percentage
If you want to calculate what percentage off a sale price represents: Discount % = ((Original − Sale) ÷ Original) × 100.
Example: A blender was $80, now $60. Discount % = ((80 − 60) ÷ 80) × 100 = (20 ÷ 80) × 100 = 25% off.
How to Find the Original Price
If you know the sale price and the discount percentage, work backward: Original Price = Sale Price ÷ (1 − Discount/100).
Example: Shoes are $75 after a 25% discount. Original = 75 ÷ (1 − 0.25) = 75 ÷ 0.75 = $100.
Discount Quick Reference Table
| Original Price | 10% Off | 20% Off | 30% Off | 40% Off | 50% Off |
|---|---|---|---|---|---|
| $50 | $45 | $40 | $35 | $30 | $25 |
| $100 | $90 | $80 | $70 | $60 | $50 |
| $150 | $135 | $120 | $105 | $90 | $75 |
| $200 | $180 | $160 | $140 | $120 | $100 |
| $500 | $450 | $400 | $350 | $300 | $250 |
How to Calculate Stacked Discounts
When a retailer offers multiple discounts (e.g., 20% off, then an additional 10% coupon), they apply sequentially, not additively. A 20% discount followed by a 10% discount is not the same as a 30% discount.
Example: A $200 item is 20% off (= $160), then you apply a 10% coupon. The 10% applies to $160, not $200: 10% of $160 = $16. Final price = $160 − $16 = $144. This is a 28% total discount, not 30%. To find the combined discount: 1 − (0.80 × 0.90) = 1 − 0.72 = 28%.
How to Spot Fake Discounts
Some retailers inflate the “original price” before marking it down — a practice known as “reference price inflation.” The item may have never actually sold at the stated original price, making the discount misleading. Before trusting a sale price, check the item’s price history using tools like CamelCamelCamel (for Amazon), Google Shopping, or browser extensions that track historical prices. A genuine 40% discount looks very different from a price that was quietly raised last week just to be “marked down” today.
Use Our Free Discount Calculator
Find the exact sale price and your savings instantly with our free Discount Calculator. Enter the original price and discount percentage to get the result in one click.
Frequently Asked Questions
Does sales tax apply before or after the discount?
In most jurisdictions, sales tax is calculated on the discounted price (after the discount is applied). This means you save on both the item price and the tax. For example, a $100 item with a 20% discount and 8% tax: sale price = $80, tax = $80 × 0.08 = $6.40, total = $86.40.
What is the difference between a discount and a rebate?
A discount reduces the price at the point of sale — you pay less immediately. A rebate is a partial refund submitted after the purchase. Rebates require effort (mailing forms or submitting receipts online) and have an expiration date. Studies show that 20–40% of rebates go unclaimed, which is why retailers use them — the advertised savings are not always realized by the buyer.
Is a “Buy One Get One Free” the same as 50% off?
No. “Buy one get one free” means you get 2 items for the price of 1 — an effective discount of 50% per item only if you were going to buy two anyway. If you only wanted one item, it is not actually a 50% saving because you are spending more than you originally planned. A true 50% discount means each individual item is half price regardless of quantity.