Percentage Calculator
MathCalculate percentages, increase or decrease, ratios and change between values with multiple modes for everyday math and financial quick checks.
10025.0000%+300.00%150-50About Percentage Calculator
Percentages sound simple, yet it is easy to mix up which number is the base. This tool computes the five most common percentage results at once: X% of Y, what percent X is of Y, the percent change from X to Y, X increased by Y%, and X decreased by Y%. Type just two numbers, X and Y, and the five cards update live, each showing the underlying formula so you can double-check. Every calculation runs locally in your browser, so the prices, sales figures, or other numbers you enter never leave your device. Tip: Bookmark this tool for quick access whenever you need mathematical calculations. All computation happens locally in your browser with instant results.
How to Use
- Open the Percentage Calculator tool page
- Enter or paste your data into the input area
- View the real-time results and use the copy button to get the output
Use Cases
- Discount pricing — Enter the original price and discount rate, then read the "decrease by Y%" card for the sale price.
- Growth rate — Plug in last and this month to see the period-over-period change as a percentage.
- Share analysis — Enter a single value and the total to learn its share of the whole.
- Tax totals — Use "increase by Y%" on a pre-tax amount to get the tax-inclusive total.
- Tip splitting — Add a service-charge percentage to a bill amount to find the total owed.
- Commission split — Calculate what percentage each partner's share represents of the total transaction to divide revenue fairly.
- Performance metrics — Compute the percent change in page load time or error rate between two release cycles.
FAQ
What is the difference between "X is what % of Y" and "% change X to Y"?
The first is X÷Y, the share of X within Y. The second is (Y−X)÷X, the rise or fall relative to the base X. Their denominators differ, so they mean entirely different things.
Why does the change card show an infinity symbol?
When the base X is 0, the change formula divides by zero, which is undefined, so it is shown as ∞. Make sure the starting value is not zero.
How many decimals are kept?
Ratio and change results keep 2 to 4 decimals; amount results keep up to 4 significant decimals with thousands grouping, avoiding distracting long-tail digits.
If I raise by 10% then cut by 10%, do I return to the original?
No. Multiplying by 1.1 then 0.9 equals 0.99, which is 1% below the start. Chain the "increase" and "decrease" cards to verify this classic misconception.
Are negatives and decimals supported?
Yes. X and Y accept negatives or decimals, handy for temperature gaps or loss rates; a zero denominator shows ∞ instead of throwing an error.
Any browser compatibility requirements?
This tool works in all modern browsers (Chrome, Firefox, Edge, Safari). No plugins or extensions required.
Can I use it offline?
After initial load, most features work offline. The core logic runs entirely in your browser with no network dependency.
Comments
Comments are stored locally in your browser. Configure Giscus for cloud-based comments.