Financial Tool

Percentage Change

Calculate the percent increase or decrease between two values.

Σ The Formula

( (New Value - Old Value) / |Old Value| ) * 100

Real World Examples

Basic Percentage
What is 15% of 200? → 30
Reverse Calculation
30 is what % of 200? → 15%
Sales Discount
Original price $80, 25% off → Save $20, Pay $60
Grade Calculation
Scored 85 out of 100 points → 85% grade

# About This Calculator

Percentages are one of the most fundamental concepts in mathematics, representing a portion of a whole as a fraction of 100. The word "percent" comes from the Latin "per centum," meaning "by the hundred."

Percentages are used everywhere in daily life: calculating discounts while shopping, understanding interest rates on loans, analyzing business growth, determining tax amounts, and interpreting statistics in news and research. Mastering percentage calculations is essential for financial literacy and data interpretation.

This calculator handles three common percentage scenarios: finding what percentage one number is of another ("X is what % of Y?"), calculating a percentage of a number ("What is X% of Y?"), and determining percentage change between two values ("% Change from X to Y").

Unlike manual calculation which can be error-prone with decimals, this tool provides instant, accurate results for any percentage problem, making it invaluable for students, professionals, and anyone dealing with numbers regularly.

How To Use

  1. Enter the Old Value (Start).
  2. Enter the New Value (End).
  3. Click Calculate Change.

Frequently Asked Questions

How do I calculate percentage manually?+

To find what percentage X is of Y, divide X by Y and multiply by 100. For example, to find what percentage 25 is of 200: (25 ÷ 200) × 100 = 12.5%. To find X% of Y, multiply Y by X and divide by 100.

What's the difference between percentage and percentile?+

A percentage is a fraction of 100, while a percentile indicates the value below which a percentage of data falls. For example, scoring in the 90th percentile means you scored better than 90% of test-takers, not that you got 90% of questions correct.

Can percentages be greater than 100%?+

Yes! Percentages over 100% indicate values greater than the original whole. For example, if sales increased from 50 to 120 units, that's a 140% increase (120 is 240% of 50). This is common in growth metrics and comparisons.

How do I calculate percentage increase or decrease?+

Use the formula: ((New Value - Old Value) / Old Value) × 100. Positive results show increase, negative show decrease. For example, price going from $80 to $100 is ((100-80)/80) × 100 = 25% increase.

What are common mistakes when calculating percentages?+

Common errors include: confusing the base value, mixing up percentage increase vs. percentage of total, forgetting to multiply by 100, incorrectly handling percentage points vs. percentages, and adding percentages from different bases.

Why can't I just add percentages together?+

Percentages represent different bases, so adding them directly is incorrect. For example, a 50% increase followed by a 50% decrease doesn't return to the original value - you end up 25% lower because each percentage applies to a different base number.

About

Percentages are one of the most fundamental concepts in mathematics, representing a portion of a whole as a fraction of 100. The word "percent" comes from the Latin "per centum," meaning "by the hundred."

Percentages are used everywhere in daily life: calculating discounts while shopping, understanding interest rates on loans, analyzing business growth, determining tax amounts, and interpreting statistics in news and research. Mastering percentage calculations is essential for financial literacy and data interpretation.

This calculator handles three common percentage scenarios: finding what percentage one number is of another ("X is what % of Y?"), calculating a percentage of a number ("What is X% of Y?"), and determining percentage change between two values ("% Change from X to Y").

Unlike manual calculation which can be error-prone with decimals, this tool provides instant, accurate results for any percentage problem, making it invaluable for students, professionals, and anyone dealing with numbers regularly.

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