Percentage Calculator
MathCalculate percentages, increase or decrease, ratios and change between values with multiple modes for everyday maths and financial quick checks. Five results.
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About 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. For example, X=200, Y=15 returns 15% of 200 is 30, 15 as 7.5% of 200, 200 to 230 is +15%, and more — five results at once.
How to Use
- Open the Percentage Calculator tool
- Enter the values to calculate
- Adjust the output options as needed
- Click the Calculate button; results appear in real time
- Copy or export the result
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.