Percentage Change Calculator

What Is Percentage Change?

Percentage change measures how much a value has increased or decreased relative to its original value, expressed as a percentage. If a stock price moves from $50 to $65, the percentage change is +30%. If it drops from $65 to $50, the percentage change is -23.1%. Notice that the same $15 difference produces different percentages because the starting value is different. Percentage change is the standard way to compare changes across different scales and is used in finance, economics, science, and everyday comparisons.

How to Calculate Percentage Change?

The formula is: Percentage Change = ((New Value - Old Value) / Old Value) times 100. A positive result indicates an increase, a negative result indicates a decrease. If your rent went from $1,200 to $1,350, the percentage change is ((1350 - 1200) / 1200) times 100 = 12.5% increase. If your electricity bill dropped from $180 to $150, the change is ((150 - 180) / 180) times 100 = -16.7% decrease. Enter your old and new values in the calculator above for instant results.

Percentage Increase vs Percentage Decrease

Percentage increase and decrease are both forms of percentage change. For increase specifically: ((New - Old) / Old) times 100. For decrease: ((Old - New) / Old) times 100, which gives a positive number representing the reduction. A product that goes from $80 to $100 has a 25% increase. Going from $100 back to $80 is a 20% decrease. This asymmetry is important: a 50% increase followed by a 50% decrease does not return to the original value. $100 plus 50% = $150, then $150 minus 50% = $75, not $100. The order and base value matter.

Percentage Difference vs Percentage Change

Percentage change has a clear starting point (old value). Percentage difference compares two values without designating either as the original. The formula uses the average of the two values as the denominator: Percentage Difference = (|A - B| / ((A + B) / 2)) times 100. Comparing cities with populations of 200,000 and 250,000: percentage difference is 22.2% (using their average of 225,000 as the base), while percentage change from the first to the second is 25% (using 200,000 as the base). Use percentage change when one value clearly came before the other. Use percentage difference when comparing two independent values.

Common Percentage Change Applications

Investors calculate portfolio returns as percentage change. Businesses track revenue growth quarter over quarter and year over year. Economists measure inflation as the percentage change in price indices. Real estate agents compare home values over time. Scientists measure experimental changes relative to control groups. Sales teams track percentage change in conversion rates. Weight loss is expressed as a percentage of starting weight. Any situation where you need to communicate "how much did this change?" uses percentage change as the standard metric.

Year-Over-Year and Month-Over-Month

Business and economics frequently use percentage change over specific time periods. Year-over-year (YoY) compares the same metric to the same period one year ago, removing seasonal effects. Month-over-month (MoM) compares to the previous month, capturing recent trends but including seasonal noise. Quarter-over-quarter (QoQ) balances the two. A company reporting 15% YoY revenue growth means this quarter's revenue is 15% higher than the same quarter last year. These time-based percentage changes are the standard language of earnings reports, economic data releases, and business performance reviews.

How to Calculate Compound Percentage Change?

When a value changes by different percentages over multiple periods, the total change is not the sum of individual percentages. If a stock rises 20% one year and falls 15% the next, the total change is not +5%. Starting at 00: after +20% = 20, after -15% = 02. The actual total change is +2%. The formula for compound percentage change is: Total = ((1 + r1) times (1 + r2) times ... - 1) times 100, where r values are the decimal rates (positive for increase, negative for decrease). This compounding effect is why investment returns reported as averages can be misleading. A portfolio that goes up 50% then down 50% is not breakeven. It is down 25% because 100 times 1.5 times 0.5 = 75.

How to Calculate CAGR?

Compound Annual Growth Rate (CAGR) smooths multi-year percentage changes into one annualized rate. The formula is: CAGR = (Ending Value / Beginning Value)^(1/years) - 1. If an investment grew from 0,000 to 8,000 over 5 years, CAGR = (18000/10000)^(1/5) - 1 = 12.47%. This means the investment grew at an equivalent rate of 12.47% per year, even though actual yearly returns varied. CAGR is the standard metric for comparing investments, revenue growth, and economic performance across different time periods.

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