Quick lookup
Sale price by discount (what you pay, what you save)
Quick reference for the sale price at common discount percentages. Format: final price you pay / amount you save.
| Original price | 20% off | 30% off | 50% off | 70% off |
|---|---|---|---|---|
| $20 | $16 / $4 | $14 / $6 | $10 / $10 | $6 / $14 |
| $50 | $40 / $10 | $35 / $15 | $25 / $25 | $15 / $35 |
| $80 | $64 / $16 | $56 / $24 | $40 / $40 | $24 / $56 |
| $100 | $80 / $20 | $70 / $30 | $50 / $50 | $30 / $70 |
| $150 | $120 / $30 | $105 / $45 | $75 / $75 | $45 / $105 |
| $200 | $160 / $40 | $140 / $60 | $100 / $100 | $60 / $140 |
| $500 | $400 / $100 | $350 / $150 | $250 / $250 | $150 / $350 |
Stacked discounts don't add: 20% then 10% off is 28% total, not 30%. Use the stacking feature above to model 'extra X% at checkout' deals correctly.
Overview
What this calculator does
The discount calculator finds the sale price and how much you save from any percentage off. It handles stacked discounts (the 'extra 10% at checkout' kind), shows the effective total percentage, and can add sales tax to give you the real out-the-door cost.
The math
The formula
Single discount
sale price = original × (1 − discount). For 25% off $80: 80 × 0.75 = $60. You save 80 × 0.25 = $20.
Finding the original price
If you know the sale price and the discount: original = sale price / (1 − discount). A $60 item at 25% off was originally 60 / 0.75 = $80. Useful for checking whether a 'was $X' claim is honest.
Important
Stacked discounts: the math that trips people up
When you stack discounts, they multiply — they don't add. This is the single most common shopping math error.
20% off then an extra 10% off a $100 item:
- Step 1: 20% off $100 = $80
- Step 2: 10% off $80 = $72
- Total off: $28, or 28% — NOT 30%
The order doesn't matter (10% then 20% gives the same $72), but the result is always less than the sum of the percentages. The formula for two stacked discounts: effective = 1 − (1 − d1) × (1 − d2). For 20% and 10%: 1 − 0.8 × 0.9 = 0.28 = 28%.
Retailers know this
Use cases
Common shopping scenarios
Clothing clearance
End-of-season often hits 50-70% off. Stack a coupon for the real damage: 60% off + extra 20% = 68% off.
Black Friday
Compare the discounted price to the item's actual recent price, not the inflated 'list price'. Some '50% off' deals are barely below normal.
BOGO (buy one get one)
BOGO free = 50% off when you buy two. BOGO 50% off = 25% off the pair. Compute the per-item effective rate.
Bulk / quantity discounts
'10% off when you buy 3' only saves if you needed 3. Otherwise you spent more to save a percentage.
Membership pricing
Factor the annual membership cost into the effective discount. A 10% member discount needs enough spending to beat the fee.
Cashback stacking
Store discount + credit card cashback + portal rebate genuinely stack since they're separate. 30% off + 5% cashback ≈ 33.5% effective.
Behind the scenes
Privacy and how it runs
Runs in your browser
Common questions
How do I calculate 25% off?
Multiply the price by 0.75 (which is 1 − 0.25). $80 × 0.75 = $60. Or find the savings first: $80 × 0.25 = $20 off, leaving $60.
What's 30% off $50?
$50 × 0.30 = $15 off, so the sale price is $35. Quick mental math: 10% of $50 is $5, so 30% is $15.
How do I add tax after a discount?
Apply the discount first, then add sales tax to the discounted price — tax is charged on what you actually pay. Our optional tax field handles the order automatically.
Is a bigger percentage always a better deal?
Not necessarily. 50% off an overpriced item can still cost more than 20% off a fairly priced one. Always compare the final price against what the item actually sells for elsewhere, not just the discount size.
How do I reverse-engineer the original price?
Divide the sale price by (1 − discount as decimal). $45 after a 25% discount: 45 / 0.75 = $60 original. Handy for verifying 'reduced from' claims.
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Last reviewed: · Methodology based on US building code standards, contractor pricing surveys, and manufacturer specifications.