Calculating a discount is straightforward once you separate percent off, sale price, and savings amount. This walkthrough shows the formulas, a worked example, stacking pitfalls, and when to use a calculator instead of doing mental math at checkout.
Core discount formulas
Savings amount = original price × (discount percent ÷ 100). Sale price = original price − savings amount. You can also compute sale price = original price × (1 − discount percent ÷ 100).
Try the free discount calculator to confirm savings and final price quickly.
Worked example
A jacket lists at $80 with 25% off. Savings = 80 × 0.25 = $20. Sale price = $60. If sales tax applies on the discounted price in your area, tax is calculated after the discount unless local rules say otherwise.
Stacked discounts and coupons
Order matters. A 20% store discount then a $5 coupon is not always the same as the coupon first. Retailers define stacking rules. When in doubt, compute step by step and verify the register line items.
For tip-style percent math after tax or before tax questions, use the percentage calculator or tip calculator depending on the scenario.
Common mistakes
- Applying percent to the wrong base (pre-tax vs post-tax)
- Adding percents instead of applying them sequentially
- Forgetting shipping or fees that are not discounted
- Comparing “% off” to “% of” language carelessly
Coupon after percent-off example
List price 0 with 15% off becomes 2. A coupon after the percent-off yields before tax. If the coupon had applied first, results would differ. Always follow the retailer’s stated order, then verify on the receipt.
When comparing two stores, compute final out-the-door totals including tax and shipping rather than comparing percent badges alone.
Markdown versus percent-off language
Retailers sometimes advertise “ off” (markdown) and sometimes “20% off” (percent). Convert both to a final price before you compare. A markdown on a item is a steeper cut than 20% off the same item.
For multi-item carts, apply each rule in the order the checkout system uses. If the site applies cart-wide percents after item markdowns, your handwritten estimate should follow that sequence or the totals will disagree.
When tax is charged on the discounted merchandise total, compute tax on the post-discount base. If a jurisdiction taxes the pre-discount price in rare cases, follow the receipt, not a generic calculator assumption.
Frequently Asked Questions
How do I take 30% off a price?
Multiply the price by 0.30 for savings, or multiply by 0.70 for the sale price.
What is the difference between 20% off and paying 20%?
20% off means you pay 80%. Paying 20% means the sale price is one-fifth of the original.
Can I add two discounts together?
Not safely. Apply them in the retailer’s order, one after another.
Does tax change the discount math?
Tax is usually applied according to local rules on the taxable base after or before discounts. Check the receipt logic if the total looks off.
Conclusion
Discount math is percent-of-base arithmetic. Keep the base clear, apply one reduction at a time, and verify with a calculator when stacked offers appear.
Run the numbers in the Discount Calculator and compare with Percentage Calculator.