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Percentage Calculator

Calculate percentages, increase/decrease, and more.

Percentages are used everywhere in daily life: discounts while shopping, interest rates on loans, tips at restaurants, tax deductions, grade calculations, and performance metrics at work. Our free Percentage Calculator includes the five most common percentage calculations in one tool.

Choose the calculation you need: "What is X% of Y?" (find a percentage of a number), "X is what percent of Y?" (find the percentage rate), "X% of what is Y?" (find the original number), "Percent change from X to Y" (increase/decrease), and "Increase/decrease X by Y%".

Each calculator shows both the result and the formula used, making it a great learning tool for students and anyone wanting to understand how percentages work. All results are computed with high precision and rounded to a practical number of decimal places.

For example, if you see a $79.99 item with a 25% off tag, use "Decrease by Y%" to find the sale price ($59.99). If your portfolio went from $12,000 to $14,500, use "Percent change" to see it grew by 20.83%. The tool handles negative percentages and decreases automatically.

Frequently Asked Questions

What is the difference between percentage change and percentage difference?
Percentage change expresses the difference from the original value as a percent of the original (old → new). Percentage difference is used when comparing two values without a clear baseline and divides by their average. Our tool uses the standard percentage change formula.
Why is "percent change from 0" undefined?
Dividing by zero is mathematically undefined. If the original value is zero, any positive result represents an infinite percentage increase. In practice, use absolute dollar or unit amounts when the baseline is zero.
How do I calculate tips quickly?
For a 15% tip on a $48 bill: 10% is $4.80, half of that (5%) is $2.40, sum is $7.20. Or use our "Increase by Y%" calculator to add 15% and see the total with tip: $55.20.
Are percentages reversible? (e.g., 10% increase then 10% decrease)
No, percentages are not reversible in that way. A 10% increase on $100 makes $110, then a 10% decrease on $110 makes $99 — you end up $1 lower. This is because the base for the second calculation is higher than the first.

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