Calculating a discount is straightforward once you separate percent off, sale price, and savings amount. This walkthrough shows the formulas, worked examples, stacked coupon order, and common mistakes—then points you to tools that do the arithmetic quickly.
Core discount formulas
Sale price = original × (1 − percent/100)
Savings = original − sale price
Percent off = savings / original × 100
Use the percentage calculator when you need a quick percent of a number outside a retail framing.
Worked example
A jacket lists at $80 with 25% off. Sale price = 80 × 0.75 = $60. Savings = $20. If tax is 8% on the discounted price, tax ≈ $4.80 and out-the-door ≈ $64.80.
Stacked discounts and coupons
Order matters. A 20% off promotion followed by a $10 coupon on a $100 item becomes $80 after the percent, then $70 after the coupon. Applying the coupon first (if the store allowed it) would differ. Always follow the retailer’s stated sequence, then verify on the receipt.
Markdown versus percent-off language
A $20 markdown on a $60 item is a steeper cut than 20% off the same item. Convert both to final price before you compare stores. For multi-item carts, apply each rule in checkout order.
Discount mistakes that skew comparisons
- Comparing percent badges without final out-the-door totals
- Forgetting tax and shipping
- Assuming coupons stack when the fine print forbids it
- Using pre-discount tax bases when the receipt taxes the discounted total
Coupon after percent-off example
List price $120 with 15% off becomes $102. A $10 coupon after the percent-off yields $92 before tax. If the coupon had applied first, results would differ. When comparing two stores, compute final totals including tax and shipping rather than comparing percent badges alone.
When to use a tip or surcharge tool instead
Restaurant tipping is a different percent problem—use the tip calculator. Merchant card surcharges belong on the credit card surcharge calculator. Keep retail markdown math on this page.
Quick reference card
Percent off → multiply by (1 − percent/100) for sale price. Dollar off → subtract from the price after any required percent rules. Tax → usually on the discounted taxable merchandise total. Shipping → often after merchandise discounts unless the promo says otherwise.
Write one line: original, percent, coupon, tax, shipping, final. If the receipt disagrees, the merchant’s order of operations wins—update your notes so the next cart is faster.
For non-retail percent problems, switch to the percentage calculator rather than forcing a sale-price story onto tips or surcharges.
Frequently Asked Questions
How do I calculate 30% off quickly?
Multiply by 0.70 for the sale price, or multiply by 0.30 for the savings amount.
Are sale prices calculated before or after tax?
Retail discounts usually apply to merchandise first; tax is then charged on the taxable discounted amount per local rules.
What if two percents both apply?
Apply them in the store’s order. Sequential percents are not added into one bigger percent unless the merchant says so.
Practice with real numbers
Pick a real cart, write original, percent, coupon, tax, and shipping on one line, and compute once. Re-check with the Percentage Calculator when the arithmetic gets noisy.