How a percent off works
A percent off is a share of the original price. To get the sale price, multiply the original by one minus the discount: for 25% off, that is the original times 0.75. Take an $80 price at 25% off. The savings are $20 and you pay $60. The calculator's “Sale price” mode does exactly this.
Finding the percent off from two prices
When a tag shows an old price and a new one, the discount is the drop divided by the old price. A $50 item marked down to $35 has dropped $15, and $15 is 30% of $50, so it is 30% off. The percentage is always measured against the starting price, which is why the same $15 drop is a bigger discount on a $50 item than on a $150 one. Use “Percent off” mode for this. If the second price is higher, the tool tells you it is an increase instead.
Why 20% off plus 10% off is not 30% off
Stacked discounts multiply rather than add. Start with $100. Taking 20% off leaves $80. The extra 10% is 10% of $80, not of $100, so it takes off $8 and you pay $72. You saved $28, which is 28% of the original.
The same thing happens with any pair: each discount shrinks the price the next one is applied to. The more discounts you pile up, the further the real total falls below the sum of the percentages. Percentages can be applied in either order and give the same total. Mixing a percentage with a fixed dollar amount is different. On a $60 price, $10 off first and then 20% off leaves $40, while 20% off first and then $10 off leaves $38. The calculator's “Stacked discounts” mode handles up to three percentages.
Things the percentage does not tell you
- The starting price matters. 50% off an inflated list price can still be more than you would pay elsewhere. The percentage is only as honest as the price it is measured from.
- “Up to” is a ceiling. “Up to 60% off” means at least one item hits 60%; most may not.
- Tax and shipping come on top. They usually apply after the discount, so compare final totals when you are choosing between offers.
Looking for live discounts to run through the calculator? Browse the best Amazon deals right now, or check the dates for Black Friday and Cyber Monday. The figures on this page are made-up round numbers for illustration, not real product prices.
Frequently asked questions
- How do I calculate a percent off?
- Multiply the original price by the percent off divided by 100 to get the savings, then subtract the savings from the original price. For 25% off an $80 price, the savings are $80 x 0.25 = $20 and the sale price is $60.
- How do I find the percent off from two prices?
- Subtract the sale price from the original price, divide the result by the original price, and multiply by 100. If something drops from $50 to $35, the difference is $15, and $15 / $50 = 0.30, which is 30% off.
- Is 20% off plus an extra 10% off the same as 30% off?
- No. The second discount applies to the price left after the first one. 20% off $100 leaves $80, and 10% off $80 is $8 more, so you pay $72. That is 28% off in total, not 30%.
- Does the order of stacked percentage discounts matter?
- Not for percentages. Taking 10% off first and 20% off second also leaves $72 from $100. The order does change the result when one of the discounts is a fixed dollar amount.
- Does this calculator include sales tax or shipping?
- No. It works on the price you type in. Sales tax is usually added after discounts, and shipping is separate, so add them yourself if you want an all-in total.
- Does the calculator store what I type?
- No. The arithmetic runs in your browser and nothing you enter is sent to our servers.