Discounts and Coupons: The Real Price After the Markdown

Order matters when you stack

A $100 item with 20 percent off and a $10 coupon lands at $70 if the percent applies first, then the coupon — but at $72 if the coupon applies first. Most stores apply percent first, coupon second, then tax. The calculator follows that order and shows each step so the final number is not a mystery.

Percent off is relative, dollars off is absolute

50 percent off a $20 item saves $10; 20 percent off a $500 item saves $100. The badge size does not tell you the saving. Convert every offer to dollars saved per item or per cart before comparing deals, especially when a store advertises the discount on the most expensive item in the basket.

Tax changes the comparison

Sales tax applies to the discounted price, not the original. A $100 item at 20 percent off with 8 percent tax costs $86.40 — not $80 plus tax on $100. When comparing an online price with tax included against a local price without, put both on the same tax basis first.

The 'markup then discount' trap

A retailer can raise a price before a sale, so the 'discount' returns the item to its normal price. Check the price history or compare against other sellers before treating a badge as a deal. The calculator tells you what the math is; it cannot tell you whether the starting price was real.

Worked example

A $120 jacket at 25 percent off with a $15 loyalty coupon and 7 percent tax: $120 minus 25 percent is $90, minus $15 is $75, plus 7 percent tax is $80.25. The calculator produces the same path in one screen, so the final price is defensible before you reach the register.

Percent off vs dollar off

The two discounts are different animals. 50 percent off a $20 item saves $10; 20 percent off a $500 item saves $100. A badge that says 50 percent may be worth less than one that says 20 percent. Convert every offer to dollars saved and to the final price before comparing, and remember that stacking a percent off with a fixed coupon usually applies in the store's chosen order — the calculator reproduces that order so the final number is defensible.

Unit price is the honest comparison

A bigger package is not always cheaper. A 12-ounce jar at $4.50 is 37.5 cents per ounce; a 24-ounce jar at $8.20 is 34.2 cents per ounce — the bigger one wins. But the same math can flip with a coupon or a sale: apply the discount to the package price first, then compare per-unit. Shelf tags already show unit prices in many stores; when they do not, the quick division beats guessing.

Common mistakes

Trusting the discount badge instead of the final price. Applying tax to the original price instead of the discounted price in a comparison. Forgetting that a coupon may not stack with a sale, or that store loyalty programs reset prices. And comparing packages by size alone instead of unit price after discounts.

Decision checklist

Convert every offer to the final price: original, minus percent, minus coupons, plus tax in the store's order. Compare per-unit after discounts, not just package size. Check price history or another seller before trusting a 'was' price. Then decide on the final dollar figure — the badge is marketing; the register is the truth.

Stacking order matters, quantified

On a $100 item with 20 percent off and a $10 coupon: percent-first gives $70, then tax at 8 percent on the discounted price makes $75.60. Coupon-first gives $90, then 20 percent off makes $72, plus tax makes $77.76. The store's order changes the total by more than $2 on a $100 item — and the calculator applies the same order you specify, so the estimate matches the register.

Seasonal and clearance math

Clearance discounts stack differently than regular sales. An item already marked 30 percent off that gets an extra 20 percent at the register is not 50 percent off — it is 44 percent off (0.70 × 0.80 = 0.56, so 44 percent off the original). The calculator handles sequential discounts correctly, which is exactly where shoppers routinely overestimate the saving.

The compare-before-you-buy test

A sale only matters relative to the alternative. The same $80 item at 25 percent off is $60; the same item at another store for $55 with no discount is the better buy. Convert both to final price, add shipping and tax, and compare. The calculator handles the math on one offer; the comparison is simply running it twice — once for each store — and reading the final numbers side by side.

Read the final price, not the badge

The badge is the hook; the register is the truth. Before any purchase, write down the original price, apply every percent and dollar discount in the store's order, add tax on the discounted figure, and compare the result against the same item elsewhere. The calculator compresses that into one screen, so the number you walk in with is the number you can defend — and the sale you skip is as valuable as the one you take.

Sources and further reading

• Federal Trade Commission — Shopping tips
• Wikipedia — Discounts and allowances