Percentage Change Calculator

Starting Value

Ending Value

Percentage Change

25.00%

Absolute Change

2,000.00

8,000.00 rose to 10,000.00, an increase of 25.00%.

Formula

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

Percentage change is the signed size of the movement between two values, expressed as a percentage of the starting value, positive for a rise, negative for a fall. It's the general-purpose version of the calculation: unlike a decrease-only tool, it doesn't assume which direction the number moved.

Use it for everyday, non-technical comparisons where a value could plausibly go either way, this month's electricity bill against last month's, a test score against the previous attempt, one city's average commute time against another's.

Percentage Change Formula

Percentage Change = New − Old Old × 100

Old: The starting value, shown in blue, matching the first field above.
New: The ending value, shown in teal, matching the second field above.
|Old|: The absolute value of the starting figure, so a negative starting value doesn't flip the result's sign.

Notice the numerator here is New − Old, the reverse order from a decrease-only formula's Old − New. That's the entire difference between the two conventions: this one reads positive as growth, the other reads positive as decline.

How to Calculate Percentage Change

Four steps, and the sign in the last one is what makes this a change calculation rather than a decrease-only one.

Subtract the starting value from the ending value
Divide by the absolute value of the starting value
Multiply by 100
Read the sign as the direction

Percentage Change Examples

One example rising, one falling, the same four steps handle both without modification.

Example 1, Daily step count, 8,000 to 10,000

+25.00%

Identify the values Old = 8,000, New = 10,000
Subtract 10,000 − 8,000 = 2,000
Divide by the absolute old value 2,000 ÷ |8,000| = 0.25
Multiply by 100 0.25 × 100 = 25.00%
Read the sign Positive → an increase of 25.00%

A step count that climbs from 8,000 to 10,000 a day is a 25% increase, useful for tracking a fitness goal expressed as a percentage rather than a raw step count.

Example 2, Page load time, 3.2s to 2.1s

−34.38%

Identify the values Old = 3.2s, New = 2.1s
Subtract 2.1 − 3.2 = −1.1
Divide by the absolute old value −1.1 ÷ |3.2| = −0.34375
Multiply by 100 −0.34375 × 100 = −34.38%
Read the sign Negative → a decrease of 34.38%

A page that used to load in 3.2 seconds and now loads in 2.1 seconds is 34.38% faster, the negative sign here means an improvement, since load time is a metric where less is better.

Relationship to Percentage Decrease

Percentage decrease, as covered on the homepage calculator, is the special case of percentage change where the result is forced positive for a fall, it flips the numerator to Old − New so a drop always reads as a positive percentage. This page's signed convention (New − Old) is the more general form: a negative percentage change here is exactly equivalent to a positive percentage decrease there. Use this calculator when you don't know in advance which direction a number will move; use the decrease-only calculator when you specifically want a fall expressed as a positive figure.

Where Percentage Change Shows Up

Weather and Temperature Swings

Daily highs, rainfall totals, and reservoir levels are compared to seasonal averages as a percentage change, since a raw number ("2 inches of rain") means little without the context of whether that's typical.

Exam Score Changes

Comparing a retake score to a first attempt as a percentage change shows genuine improvement or decline in a way that's comparable across students who started from different baseline scores.

Traffic and Commute Volume

Transportation departments report changes in road traffic volume, transit ridership, and average commute times as a percentage change to compare periods of different overall demand.

Frequently Asked Questions

What's the difference between percentage change and percentage decrease?

Percentage change is a general-purpose, signed measure that covers movement in either direction from a single formula: positive means up, negative means down. Percentage decrease is the narrower, decrease-only convention used on this site's core calculator, where the sign is flipped so a positive result always means a fall. Same arithmetic, opposite sign convention.

Can percentage change be greater than 100%?

Yes, on the increase side without limit, a value can double (100% increase), triple (200% increase), and so on. On the decrease side it's capped at exactly −100%, which is the value hitting zero; only a value that starts negative and moves further from zero can register a change beyond that magnitude.

How do I calculate percentage change over multiple periods?

This calculator compares exactly two points: a start and an end. For a rate that holds steady across more than two periods, use a compound annual growth rate instead, see the growth rate calculator.

What does a percentage change of exactly 0% mean?

The ending value is identical to the starting value, no movement in either direction. It's a distinct case from a very small percentage change; 0% is exact equality, not just "close."

Is the percentage change the same size going up as it is coming back down?

No, and this catches almost everyone out at least once. A 40% increase from 100 lands on 140, but getting from 140 back to 100 is only a 28.57% decrease, not 40%, because the denominator changes to the larger number on the way back down.

How do I calculate percentage change when the starting value is negative?

The formula still works because the denominator uses the absolute value of the starting figure, which protects the sign of the result. A change from −50 to −20 is a 60% increase (it moved toward zero), computed as (−20 − (−50)) ÷ |−50| × 100.

What's a fast way to estimate percentage change without a calculator?

Round the starting value to the nearest convenient benchmark, 100, 1,000, whatever's close, and estimate the change against that instead. It won't be exact, but it's usually close enough to sanity-check a number someone just told you.

How is percentage change used in weather reporting?

Meteorologists express swings in rainfall, snowfall, and reservoir levels as a percentage change against a historical average for the same period, which is more informative than the raw figure alone since it accounts for how unusual a given month or season actually is.

Can I use this calculator for time durations?

Yes, as long as both values are converted to the same unit first, both in minutes, both in hours, and so on. Mixing units (like comparing 90 minutes against 1.5 as if it were hours) will silently give the wrong answer.

Why did my percentage change calculation come out different from a colleague's?

The most common cause is a swapped starting and ending value, which flips both the sign and the size of the result. The second most common cause is using different denominators, check that you both divided by the same starting figure.