How this works in your browser
Three distinct calculations share one interface because they are the three questions people actually ask. Finding a percentage of a number multiplies by the rate. Finding what percentage one number is of another divides and scales by a hundred. Percentage change divides the difference by the original value, which is the part worth being precise about: the denominator is always the starting figure, and using the ending figure instead is the single most common source of a wrong answer. That asymmetry is also why increases and decreases of the same percentage never cancel out. Everything is computed in your browser.
Percentage Calculator vs. typical online calculators
| Feature | Percentage Calculator (in-browser) | Typical online calculators |
|---|---|---|
| Where the maths runs | In your browser, on your device | Often posted to a server to compute |
| Your inputs are stored | Never - nothing is sent or saved | Frequently logged with your session |
| Works offline once loaded | Yes | No - needs a live connection |
| Ads inside the result area | None | Common on free calculators |
| Account required | No | Often, to save or export results |
| Usage limits | None - free, unlimited use | Sometimes capped per day |
Who uses Percentage Calculator
Discounts and price changes
Work out a reduction or a markup from a base price.
Comparing before and after figures
Express growth or decline as a percentage change.
Grades and test scores
Convert marks into a percentage of the total available.
Business and reporting figures
Calculate shares, margins and period-on-period changes.
How to use Percentage Calculator
- 1
Open the Percentage Calculator
Go to tools.slaytic.com and open the Percentage Calculator. No sign-up or account required.
- 2
Choose your calculation
Pick percentage of a number, one number as a percentage of another, or percentage change.
- 3
Enter your values
The result appears immediately, to two decimal places.
- 4
Check the direction
For percentage change, a negative result means a decrease.
Frequently asked questions
What percentage calculations are supported?
Three common cases: finding X% of a number, finding what percentage one number is of another, and calculating percentage increase or decrease between two values.
Can it calculate percentage change with negative results?
Yes, if the second value is lower than the first, the result is shown as a negative percentage (a decrease).
Does it round the result?
Results are shown to two decimal places by default for readability.
Why does a 50% rise then a 50% fall not return me to where I started?
Because each percentage applies to a different base. A hundred rising by half becomes 150, and half of 150 is 75, not 100. Percentage changes do not cancel, which is why an investment down 50 percent needs to double to recover rather than gain 50 percent back.
What is the difference between percentage points and percent?
A rate moving from 5 to 6 has risen by one percentage point, but by twenty percent. Both are correct and they describe very different magnitudes, which is exactly why the ambiguity gets exploited in reporting on interest rates, polling and tax.
How do I remove a percentage that has already been added?
Divide rather than subtract. To strip 20 percent tax from a total, divide by 1.2. Subtracting 20 percent from the gross figure gives a different and incorrect answer, which is one of the most common everyday percentage errors.
Which calculation should I use?
Use percentage of a number for tips and discounts, percentage one number is of another for shares and pass rates, and percentage change when comparing a before and after figure.