How to Calculate Percent Change

These examples use the OLD, NEW, and %CHG keys on the

• Percent Change and Total Calculator
• Percentages Calculator

For basic percent change calculations, many CALC 1 calculators have a "Δ%"" key. See Percentage Calculation Keys. While the Δ% key only calculates percent change, our percentage calculators provide significant advantages over the Δ% key or manual calculations:

1. Reduced Errors: By automating calculations, it minimizes human error in percentage computations.
2. Ease of Use: Simply enter the known values, and let the calculator do the work.
3. Key Previews: Allows you to verify value entries at a glance, further reducing input errors.
4. Versatility: Unlike the basic Δ% key that only calculates percent change, the Percentages calculators can also determine OLD or NEW values.

Understanding Percent Change

Percent change measures the relative change between an old value and a new value, expressed as a percentage. It's commonly used in finance, statistics, and everyday situations to quantify growth or decline.

Using the Calculator Keys

• OLD: Store or calculate the original value
• NEW: Store or calculate the new value
• %CHG: Store or calculate the percent change

Percent Change Calculation Examples

Example 1: Stock Price Increase

Value	Key	Display	Description
50	OLD	50	Enter the original stock price
60	NEW	60	Enter the new stock price
	%CHG	20	Calculates the percent change

The History Detail

Calculate % Change from Old and New values
          50.00 : Old
          60.00 : New
          20.00 : % CHG

Interpretation: The stock price increased by 20%.

Example 2: Calculating the Old Value (Price Increase)

Value	Key	Display	Description
120	NEW	120	Enter the new price
20	%CHG	20	Enter the percent increase
	OLD	100	Calculates the original price

The History Detail

Calculate Old Value from New and % Change
         100.00 : Old
         120.00 : New
          20.00 : % CHG

Interpretation: If the current price of $120 represents a 20% increase, the original price was $100.

Calculating New Value from Percent Change

Example 3: Salary Increase

Value	Key	Display	Description
50000	OLD	50000	Enter the original salary
5	%CHG	5	Enter the percent increase
	NEW	52,500	Calculates the new salary

The History Detail

Calculate New Value from Old and %Change
      50,000.00 : Old
      52,500.00 : New
           5.00 : % CHG

Interpretation: A 5% increase on a $50,000 salary results in a new salary of $52,500.

Additional Notes

• A positive percent change indicates an increase, while a negative percent change indicates a decrease.
• The calculator can determine any of the three values (OLD, NEW, %CHG) when given the other two.
• Remember to interpret percent changes in context - a 100% increase doubles the original value, while a 100% decrease reduces it to zero.

Real-World Applications

• Financial analysis: comparing investment returns, analyzing sales growth
• Scientific research: measuring changes in experimental results
• Business metrics: evaluating performance improvements
• Personal finance: calculating changes in income or expenses

Understanding how to calculate and interpret percent change is valuable in many fields and everyday situations. It provides a standardized way to compare relative changes between different sets of values.