Percent Off vs Percentage
Both of these calculators speak in percent, but they answer different questions. The percent off calculator answers the shopping question: a store says 25% off, and you want to know what you pay and what you save. The percentage calculator answers the general math question: it finds a percent of a number, what percent one value is of another, or the percent change between two values. The discount question is really a percent-of question with two extra steps — multiply to find the savings, then subtract — so the two pages share arithmetic but differ in purpose and inputs.
Neither tool is financial advice: the percent off page is explicitly pre-tax and pre-fee, and both pages require a nonzero base for their division-based modes.
What each calculator does
The percent off calculator takes an original price and a discount from 0 through 100 percent. It computes the discount amount as original price times percent off divided by 100, then subtracts it to get the sale price before tax, shipping, tips, or fees. Its default example is 80 dollars at 25% off: you save 20 dollars and pay 60 dollars. It also documents why stacked discounts do not simply add — 20% off followed by 10% off the reduced price totals a 28% reduction, not 30%.
The percentage calculator has three modes. Percent-of finds the part: 20% of 80 is 16. Part-of-whole finds the rate: 20 is 25% of 80. Percent change finds the relative movement: from 80 to 100 is a 25% increase, computed as the difference divided by the absolute starting value. It labels positive, negative, and zero results as increase, decrease, and no change, and it can return values above 100 when the part exceeds the whole.
Side-by-side comparison
| Feature | Percent off calculator | Percentage calculator |
|---|---|---|
| Inputs | Original price, percent off (0–100) | Percent and whole; part and whole; from and to values |
| Outputs | Sale price and discount amount | Part, percent, or percent change |
| Core formulas | discount = P × r/100; sale = P − discount | part = r/100 × whole; ratio = 100 × part/whole; change = 100 × (to − from)/|from| |
| Scope | Sale markdowns | General percent questions |
| Limits | 0–100% discount, pre-tax | Nonzero whole and starting value |
When to use which
Use the percent off calculator when you hold a sale tag: the rate is the input and the outputs are dollars. Use the percentage calculator when the percent is what you are solving for — what percent a score improved, what percent of the goal is done, or what percent one number is of another. The percentage page sends discount shoppers to the percent off page, and the percent off page sends part-of-a-whole questions to the percentage page, so the site’s own guidance is to pick by the question you are asking rather than by the arithmetic.
Both pages warn about the same classic mistakes: 25% off is not 25 dollars off, a change from 10% to 15% is 5 percentage points but a 50% relative increase, and a zero base makes a percent-of-whole or percent-change calculation undefined.
Where to start
- Percent off calculator — sale price and savings from an advertised discount.
- Percentage calculator — percent of a number, part of a whole, or percent change.