Discount Calculator
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A discount calculator finds the sale price and savings when an item is marked down by a percentage. Enter the original price and the discount rate — the math runs instantly. Useful for shopping comparisons, evaluating coupon codes, and figuring out whether a "50% off" promotion is the deal it sounds like.
The discount applies to the original (pre-tax) price. If you also want to factor in sales tax, calculate the discounted price first, then add tax to that smaller number — taxing the discounted price is how every cash register in the country actually does it.
Key takeaway
A percentage discount is just the original price multiplied by (1 − the discount as a decimal). Once you frame discounts as "what fraction of the original am I paying?" rather than "what fraction am I saving?", stacking discounts and comparing offers gets dramatically easier.
How it's calculated
The math is two operations:
- Savings = Original price × Discount % ÷ 100
- Sale price = Original price − Savings
Equivalently, you can compute the sale price directly as
Original price × (1 − Discount % ÷ 100). So a 25% off item is the same as
paying 75% of the original — the two framings always produce the same
number.
Source: Standard percentage discount math (price × (1 − discount%))
Quick tricks
- 50% off — divide by 2. Half-off sales. $80 → $40. The fastest mental discount.
- 25% off — divide by 4 to find the savings, subtract from the original. Quarter-off sales. $80 → savings $20 → sale $60.
- Stacked discounts don't add — they compound. Anytime you see '40% off plus an additional 20% off.' That's actually 52% off, not 60%. Multiply (1 − 0.4) × (1 − 0.2) = 0.48, which means you pay 48%.
- 10% off — move the decimal one place left for the savings, subtract. Coupon-code math. $250 with 10% off → $25 savings → $225.
Examples
$80 jacket, 25% off
A $80 jacket marked down 25% saves you $20 and brings the sale price to $60. Quick check: 25% of 80 is 80 ÷ 4 = 20.
$1,499 laptop, 15% off
A $1,499 laptop at 15% off saves $224.85, dropping the sale price to $1,274.15. On larger purchases, even a modest percentage discount translates into real money — worth waiting for a sale or stacking with a credit-card cashback offer.
Frequently asked questions
How do I calculate a percentage discount?
Multiply the original price by the discount percentage, then divide by
100 — that gives you the savings amount. Subtract that from the original
price to get the sale price. So a 30% discount on a $50 item: $50 × 30 ÷ 100 = $15 saved, $50 − $15 = $35 sale price.
How do stacked discounts work?
Stacked discounts multiply, they don't add. If something is 40% off
and you have an additional 20% off coupon, you don't get 60% off — you
pay (1 − 0.4) × (1 − 0.2) = 0.48 of the original, which is 52% off,
not 60%. Retailers know shoppers expect stacking to add, which is why
promotional copy often advertises the headline percentage prominently
and leaves the math ambiguous.
Is the discount applied before or after tax?
Discounts are applied to the pre-tax price, and sales tax is calculated on the discounted total. So a $100 item at 20% off in a 9% tax jurisdiction: discount first ($100 → $80), then tax on $80 ($80 × 0.09 = $7.20), final price $87.20. This is the standard at every major US retailer.
How do I figure out the original price from a sale price and discount?
Divide the sale price by (1 − the discount as a decimal). For example,
if something is on sale for $60 at 25% off, the original price was
$60 ÷ (1 − 0.25) = $60 ÷ 0.75 = $80. This is useful for evaluating
whether a "was $999, now $499" claim is genuine or whether the "was"
price was inflated to make the discount look bigger.