Calculate sale price, savings and discount percentage — free, instant, no signup required
A discount calculator helps shoppers, retailers, and budget-conscious buyers figure out exactly how much a sale will cost or how much they'll save. Sale tags often advertise percentages without showing the final price, which can make it hard to know if a deal is really good. The FileTools Discount Calculator handles three different scenarios: calculating the sale price from an original price plus a discount percentage; finding the discount percentage when you know both prices; and reverse-engineering the original price from a sale price and a percentage. Quick preset buttons (5%, 10%, 15%, 20%, 25%, 30%, 50%, 70%) cover the most common discounts. All calculations happen instantly in your browser as you type — no Calculate button needed.
Common use cases: shopping during Black Friday, Cyber Monday, or seasonal sales to compare deals; calculating final prices on clearance items; checking if "70% off" is really a better deal than "buy one get one free"; verifying that a sale price advertised by a retailer matches the discount they claim; figuring out coupon savings before checkout; setting prices in your own retail or e-commerce store; calculating your gross margin after a promotion; comparing two competing sale offers; budgeting for a planned purchase; and reverse-checking the suspicious "$199 was $499" claim that's everywhere online.
📦 Original Price + Discount %: the standard mode. Enter what something originally costs and the discount percentage to find your sale price and savings.
🔍 Find Discount %: enter both the original price and the sale price to find what discount percentage was applied. Useful when retailers show two prices but no percentage.
↩️ Find Original Price: enter a sale price and the discount percentage to discover what the item originally cost. Useful for verifying a "was/now" advertised sale.
Sale price formula: Sale = Original × (1 − Discount/100)
Savings formula: Savings = Original × Discount/100
Discount percent formula: Discount % = (Savings / Original) × 100
Stacked discounts: a 20% + 10% stack is NOT 30%. It's: (1 − 0.20) × (1 − 0.10) = 0.72, meaning 28% total off, not 30%. Discounts compound, they don't add.
Quick mental math: 50% off = half · 25% off = quarter off · 75% off = pay only a quarter · 10% off = move decimal one left.
1. Choose a mode: Original + Discount, Find Discount %, or Find Original Price
2. Enter your numbers in the input fields
3. Use preset percentage buttons (5% to 70%) for instant common values
4. Results update live: original price, savings, final price, discount percentage
5. Switch modes anytime to verify a deal from different angles
✅ 100% free — no signup, no ads in tool, no tracking
✅ Three calculation modes for any discount question
✅ Quick preset buttons for common discounts
✅ Live updates as you type — no Calculate button
✅ Shows savings highlighted in green
✅ Client-side only — your numbers never leave your device
✅ Works on Windows, Mac, Linux, Android, iOS — any browser
To find the sale price after a discount, multiply the original price by the discount percentage and divide by 100, then subtract from the original. For example, 20% off $100 is $100 − ($100 × 20 ÷ 100) = $80. The FileTools Discount Calculator does this instantly as you type.
Switch to "Find Discount %" mode, enter the original price and the sale price, and the calculator shows the discount percentage. The formula is: ((Original − Sale) ÷ Original) × 100. Example: a $100 item sold for $80 = a 20% discount. Useful when you see a sale price and want to know if the discount is meaningful.
Switch to "Find Original Price" mode, enter the sale price and the discount percentage, and the calculator shows what the item cost before the discount. Useful for verifying that a sale is actually as good as advertised, or when the original price isn't clearly shown.
When discounts are stacked (like 30% off then an additional 10% off), they apply sequentially, not added together. To calculate, run the calculator twice: first apply 30% off the original price, then apply 10% off that result. A 30% + 10% stack is actually 37% off total — not 40%.
No. All calculations happen entirely in your browser using JavaScript — nothing is uploaded, logged, or stored. Your prices stay private on your device. The calculator works offline once the page is loaded.
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