How do I calculate X% of Y?

Multiply Y by X/100. Example: 12% of 500 = 500 × 0.12 = 60.

How to compute percentage change between two values?

Percentage change = (new − old) ÷ old × 100. Use the calculator's percentage change tool for quick results.

Percentage Calculator

Quick calculators for common percentage tasks: compute X% of Y, find what percent A is of B, percentage change between two values, and increase or decrease a value by a percentage.

1) Calculate X% of Y — Enter percentage (X) and number (Y)

2) Find what percent A is of B — Enter A and B

3) Percentage change — Old value New value

4) Increase / Decrease a value by % — Enter value Percentage to apply (+ for increase, − for decrease)

Formulas used

1) X% of Y
Result = Y × (X / 100)

2) Find percent
Percent = (A / B) × 100

3) Percentage change
% Change = ((New − Old) / Old) × 100

4) Increase / Decrease
Adjusted = Base × (1 + P/100) where P is positive (increase) or negative (decrease).

Quick Reference

Operation	When to use
X% of Y	Compute tax, discount, commission, portion of a total
Find percent	Determine share of total (e.g., test score percent)
Percentage change	Measure increase or decrease between two values (growth, inflation)
Increase/Decrease	Apply discount, markup, tax or adjustment

These percentage tools are practical for shopping discounts, taxes, grade calculations, financial growth rates, and quick conversions used in daily life and business. Enter values, press the relevant button, and get immediate results with a short plain-language explanation.

When to use this calculator

Use it when you need to calculate discounts, taxes, profit margins, rate-of-change between values, or to convert ratios to percentages quickly. It's also handy for school/homework and quick finance checks.

How it works (plain explanation)

The calculator uses the standard percentage arithmetic shown above. For change calculations we display the direction (increase or decrease) and the percentage magnitude. For adjustments we show the new value and the absolute difference.

Factors to watch

Watch for zero or near-zero denominators (e.g., computing percentage change from 0 is undefined). Use absolute values where appropriate, and be explicit whether percentages relate to whole or part to avoid ambiguity.

Frequently asked questions

What if I want a percentage of a percentage? Multiply progressively: (Y × (X/100)) × (Z/100) or compute combined percent directly.

Is percent change symmetrical? No — a 50% increase followed by a 50% decrease does not return you to the original value.

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Disclaimer: This calculator is for simple arithmetic and educational purposes only. Verify results for critical financial decisions or consult a professional where needed.