Percent Change Calculator

Enter any two numbers to instantly see the rate of change (direction, magnitude, and absolute difference) in one calculation.

How It Works

This tool calculates the rate at which a value shifted between two points. Enter any starting figure as the old value, such as a stock price, salary, weight, or monthly expense, then type the current figure as the new value.

The calculator subtracts old from new, divides by the absolute old value, and multiplies by 100. A positive result means growth, while a negative result signals a decline.

Percentage change normalizes raw differences into a single comparable metric. A $50 gain on a $500 investment (10%) carries more weight than $50 on a $50,000 portfolio (0.1%), even though the dollar amounts match.

Understanding Each Variable

Old Value: the baseline or starting figure before any change occurred
New Value: the updated or most recent figure you are comparing
|Old|: absolute value of the starting figure, ensuring the sign is handled correctly
× 100: converts the decimal result into a readable percentage

What Is the Formula?

One universal equation handles both increases and decreases.

Universal Formula

% Change = ( New − Old ) ÷ |Old| × 100

Subtract the old value from the new, divide by the absolute old value, then multiply by 100. Positive result = increase; negative = decrease.

Live Example

old

new

% Change +17.21%

Absolute +7.78

Step by Step Worked Example

Scenario: Your monthly rent was $1,200 last year and just increased to $1,350.

Step 1: Subtract

$1,350 − $1,200

= $150

Step 2: Divide

$150 ÷ $1,200

= 0.125

Step 3: Multiply

0.125 × 100

= 12.50%

Your rent increased by 12.50%, which equals $150 more per month. Since the new value is larger, the result is positive, confirming an upward shift.

Real World Reference Values

Scenario	Old Value	New Value	% Change	Direction
Salary Raise	60,000	66,000	+10.00%	📈
Gas Price Drop	4.5	3.6	-20.00%	📉
Stock Gain	45.2	52.98	+17.21%	📈
Rent Increase	1,200	1,350	+12.50%	📈
Weight Loss	185	172	-7.03%	📉
Revenue Growth	250,000	312,500	+25.00%	📈
Price Inflation	2.99	3.49	+16.72%	📈
Score Improvement	680	745	+9.56%	📈

⚡ Recommended Tools

Related Percentage Tools

Specialized calculators for every percentage problem, from retail shopping markdowns to salary budgeting.

Percent Increase

Percent Decrease

Percent Difference

Percent of Total

Common Questions

Is percent change the same as percent difference?

No: percent change measures a directional shift from old to new, while percent difference symmetrically compares any two values regardless of order.

Can the result be a negative number?

Yes, a negative result means the value decreased: going from $100 to $80 is a −20% change.

What happens if the starting value is zero?

The calculation is undefined because it requires dividing by the old value, and division by zero is not possible.

How do I measure growth over multiple time periods?

Use the compound formula: Total Change = ((Final ÷ Initial) − 1) × 100, instead of adding individual period percentages together.

What is the difference between percentage points and percent change?

Percentage points measure the raw gap between two rates (3% to 5% = 2 points), while percent change shows relative growth (3% to 5% = 66.7% change).

Is there a maximum percent increase?

No, increases have no upper limit (tripling is +200%), but decreases cap at −100% since values can only drop to zero.

How do investors use this metric?

They track stock returns, compare portfolio performance across different asset sizes, and calculate annualized or cumulative growth rates.

Does swapping the old and new values change the answer?

Yes: the formula divides by the old value, so reversing the inputs changes the reference point and produces a different percentage.