What is a Discount Calculator?
This calculator computes discounted prices, discount rates, and original prices from a percentage discount.
How it's calculated
Discounted price = original price × (1 − discount rate)
Discount rate = (original − discounted) ÷ original × 100
Stacked discounts don't simply add
30% off plus an additional 20% off is not 50% off — it's actually 44% off. 100 → 70 (after 30%) → 56 (after 20% more off the already-discounted price). The second discount applies to the reduced price, not the original. Conversely, a '50% off, then half price' promotion actually works out to 75% off total.
Good to know
- Raising a price and then lowering it by the same percentage leaves it below the original. $100 → +20% = $120 → −20% = $96.
- 'Buy one, get one' and '50% off' aren't equivalent — BOGO requires buying two items, so total spending is higher; a straight 50% discount is cheaper if you only need one.
- Prices ending in $.99 or similar exploit the tendency to focus on the leftmost digit, making the price feel cheaper than it actually is.
- In a 'up to 70% off' promotion, the key word is 'up to' — items actually at 70% off are often a small fraction of the total selection.
- The sales tax trap works the same way: subtracting a flat percentage from a tax-included total is mathematically wrong — you have to divide, not subtract.
Frequently asked questions
Q. What's the total discount for 30% off plus an additional 20% off?
44%. You end up paying 56% of the original price.
Q. How do I find the original price from a discounted price?
Discounted price ÷ (1 − discount rate). An $80 price after 20% off means the original was $100.
Q. How do I remove sales tax from a tax-included total?
Divide by (1 + tax rate), not subtract a flat percentage.