How to Use This Calculator
- 1
Enter the original price
Use the full sticker or list price before any markdown. This is the number the store's percent-off claim is measured against.
- 2
Add the discount percentage
Type the advertised markdown — 30 for 30% off. The sale price and dollar savings update as you type.
- 3
Stack an extra coupon if you have one
Promo codes like 'extra 10% off sale items' go in the optional field. The calculator correctly applies them to the already-reduced price rather than the original.
- 4
Check the effective discount
The last stat shows your true total markdown from the original price — the honest number to compare across deals, especially when discounts are stacked.
How It Works
A percent-off discount converts the percentage into dollars against the original price, then subtracts:
Sale price = Original price − Amount saved
When a second coupon stacks on top, the whole formula runs again with the sale price as the new starting point. That's why stacked percentages can't simply be added: the second discount works on a smaller base, so “30% off plus an extra 10% off” is a 37% total markdown, not 40%.
Worked example
A sweater lists for $79.99 and the rack says 30% off. You save 79.99 × 0.30 = $24.00 and pay $55.99.
Now apply an extra 10% off coupon. It works on the $55.99 sale price — not the original — taking off another $5.60 for a final price of $50.39.
Total savings: $29.60 on $79.99, an effective 37% discount. Adding the percentages would have promised 40% — the missing 3 points are the second coupon working on a smaller number.
Frequently Asked Questions
How do I quickly figure 20% or 30% off in my head?
Anchor on 10% — just slide the decimal one place left — then scale. On a $79.99 item, 10% is about $8, so 20% off saves roughly $16 (pay ~$64) and 30% saves about $24 (pay ~$56). Another shortcut: 20% off means paying 80% of the price, so multiply by 8 and drop a digit.
Do stacked discounts add together?
No — they apply one after another, each to a smaller base. Take 30% off plus an extra 10% off: the item first drops to 70% of its price, then to 90% of that, leaving 0.70 × 0.90 = 63% of the original. That's a 37% total discount, not 40%. The more coupons you stack, the wider the gap between the advertised sum and reality.
Is 70% off too good to be true?
Sometimes. Retailers can inflate the 'original' price — a tactic called anchor pricing — so a 70% markdown lands near what the item ordinarily sells for anyway. Before trusting a dramatic percentage, check the item's typical street price elsewhere or on a price-history tracker. Judge the deal by the final dollar amount, not the size of the percent-off badge.
Is the discount applied before or after sales tax?
Before. U.S. stores discount the shelf price first, then charge sales tax on what you actually pay. A $79.99 item at 30% off in a state with 8% tax rings up as $55.99 plus $4.48 tax, about $60.47 total. The discount effectively shrinks your tax bill too, since you're taxed on the smaller amount.
How do I find the original price from a sale price?
Divide the sale price by (1 minus the discount as a decimal) — don't add the percentage back. If something costs $55.99 after 30% off, the original was 55.99 ÷ 0.70 = $79.99. Adding 30% to $55.99 instead would give $72.79, which is wrong because the 30% was taken from the larger original number.
Which is better: percent off or dollars off?
Convert both to dollars on your actual item and compare. A $15-off coupon beats 15% off for anything under $100, while the percentage wins above it. On a $79.99 purchase, $15 off saves $15 but 15% saves only $12. Stores often push percentage deals on cheap items precisely because they sound bigger than they are.