Percent Change Calculator – Increase or Decrease

Use this percent change calculator to find how much a value increased or decreased compared with its original value. Enter the starting value and new value to see the percentage change, amount changed, direction, and a step-by-step calculation.

Formula: ((New − Original) ÷ Original) × 100

A positive result means an increase, while a negative result means a decrease.

How did 100 change to 150?

Original valueExample: 100

New valueExample: 150

Percentage change

50% Increase

100 increased to 150, which is a 50% increase.

Original value: 100
New value: 150
Amount changed: +50
Percent change: +50%
Direction: Increase

Original100

New150

How it is calculated

Find the amount of change: 150 − 100 = 50.
Divide by the original value: 50 ÷ 100 = 0.5.
Convert to a percentage: 0.5 × 100 = 50%.
100 increased to 150, which is a 50% increase.

How to Calculate Percent Change

Subtract the original value from the new value.
Divide the difference by the original value.
Multiply by 100.

((New − Original) ÷ Original) × 100

A positive result is an increase, a negative result is a decrease, and zero means the value did not change.

Questions This Calculator Can Answer

Try one of these common percent-change examples. Select one to load it into the calculator.

Real-World Percentage Change Examples

Revenue growth

Revenue rises from $80,000 to $100,000. The difference is $20,000, and 20,000 ÷ 80,000 × 100 = 25%.

Revenue increased by 25%.

Price decrease

A product falls from $150 to $120. The difference is −$30, and 30 ÷ 150 × 100 = 20%.

The price decreased by 20%.

Salary increase

A salary goes from $50,000 to $55,000. The difference is $5,000, and 5,000 ÷ 50,000 × 100 = 10%.

The salary increased by 10%.

Monthly bill increase

An electricity bill rises from $180 to $225. The difference is $45, and 45 ÷ 180 × 100 = 25%.

The bill increased by 25%.

Inventory decrease

Inventory drops from 1,000 units to 850 units. The difference is −150, and 150 ÷ 1,000 × 100 = 15%.

Inventory decreased by 15%.

Website traffic growth

Monthly visitors go from 40,000 to 50,000. The difference is 10,000, and 10,000 ÷ 40,000 × 100 = 25%.

Traffic increased by 25%.

Common Percent Change Examples

Original	New	Percent change
50	75	50% increase
80	100	25% increase
100	120	20% increase
100	150	50% increase
100	200	100% increase
200	250	25% increase
100	90	10% decrease
100	80	20% decrease
150	100	33.33% decrease
200	100	50% decrease

Why Doesn't a 50% Increase Followed by a 50% Decrease Return to the Starting Value?

Start at 100. Increase it by 50%: 100 + 50 = 150. Now decrease 150 by 50%: 50% of 150 is 75, so 150 − 75 = 75.

100 → 150 → 75

A 50% increase followed by a 50% decrease leaves you at 75 — a 25% net decrease from the original value, not a return to 100.

The reason is the base: the increase is calculated from 100, but the decrease is calculated from the new base of 150. The two percentages are applied to different starting amounts.

The reverse is also true. If a value falls 50% from 100 to 50, it must then increase by 100% to get from 50 back to 100.

Why Is the Percent Increase Different From the Percent Decrease?

Going from 100 to 150 is an increase of 50 ÷ 100 = 50%. Going back from 150 to 100 is a decrease of 50 ÷ 150 = 33.33%.

The absolute difference is 50 in both directions, but the percentage differs because each direction divides by a different original value. Percent change is not symmetrical.

Percent Change vs. Percentage-Point Change

These are not the same measure, and mixing them up changes the meaning of a figure.

An interest rate rises from 5% to 6%. That is an increase of 1 percentage point, but the relative percent increase is (6 − 5) ÷ 5 × 100 = 20%.

A test pass rate rises from 60% to 75%. That is 15 percentage points, and a relative increase of (75 − 60) ÷ 60 × 100 = 25%.

Use percentage points when you are comparing two percentages directly, such as rates or shares. Use percent change when you want to know how large the move was relative to where it started.

Percent Change vs. Percent Difference

Percent change compares an original value with a new value and always uses the original value as the denominator — it assumes a direction in time.

Percent difference is used when neither number is naturally the original value, such as comparing two independent measurements. It typically divides by the average of the two values instead, so the answer is the same whichever number you list first.

How to Calculate Percentage Increase

Use this when the new value is larger than the original value.

((New − Original) ÷ Original) × 100

From 80 to 100 the difference is 20, and 20 ÷ 80 × 100 = 25% increase. The calculator above detects an increase automatically and labels the result for you.

If you already know the increase percentage and want the final number instead, use the Increase by Percentage Calculator.

How to Calculate Percentage Decrease

Use this when the new value is smaller than the original value.

((Original − New) ÷ Original) × 100

From 100 to 80 the difference is 20, and 20 ÷ 100 × 100 = 20% decrease. The general percent-change formula returns −20% for the same numbers; the negative sign simply signals the direction, which this page states as “20% decrease”.

If you know the percentage decrease and want the reduced value, use the Decrease by Percentage Calculator.

What Does a 100% Increase Mean?

A 100% increase doubles the original value. From 100 to 200 the difference is 100, and 100 ÷ 100 × 100 = 100%, so 100 increased by 100% to become 200.

A 200% increase means the value becomes three times the original: 100 → 300 is a 200% increase, because the value grew by 200 on a base of 100.

What Does a 100% Decrease Mean?

A 100% decrease reduces a positive value to zero. From 100 to 0 the difference is −100, and −100 ÷ 100 × 100 = −100%, so 100 decreased by 100%.

For a positive starting value, a decrease of more than 100% would require the value to cross below zero, which usually needs context to interpret sensibly.

Can You Calculate Percent Change From Zero?

The standard formula divides by the original value. If the original value is zero, ((New − 0) ÷ 0) × 100 is undefined, so moving from 0 to a positive value has no finite standard percentage increase.

Going from 0 to 50 should not be shown as Infinity%. This calculator states instead that percent change is undefined when the original value is zero.

What About Negative Numbers?

Percent change involving negative starting or ending values is mathematically valid but context-sensitive. When a value crosses zero, describing the result simply as an “increase” or “decrease” can be misleading.

The calculator still applies the defined formula, and shows a short caution whenever the original value is negative so you can interpret the figure in context.

Which Percentage Calculator Should I Use?

Percent Change (this calculator)

You know: Original value and new value. You want: Percentage increase or decrease. Example: 100 → 150 is a 50% increase.

What Is X% of Y?

You know: A percentage and a whole. You want: The percentage amount. Example: What is 20% of 500?

What Percent Is X of Y?

You know: A part and a whole. You want: The percentage. Example: 100 is what percent of 500?

Reverse Percentage

You know: A part and its percentage. You want: The original whole. Example: 100 is 20% of what?

Increase by Percentage

You know: An original number and a percentage increase. You want: The final increased number. Example: Increase 500 by 20%.

Decrease by Percentage

You know: An original number and a percentage decrease. You want: The final reduced number. Example: Decrease 500 by 20%.

Frequently Asked Questions

How do I calculate percent change?

Subtract the original value from the new value, divide by the original value, then multiply by 100: ((New − Original) ÷ Original) × 100.

What is the percentage increase from 100 to 150?

50%. (150 − 100) ÷ 100 × 100 = 50.

What is the percentage decrease from 150 to 100?

33.33%. (100 − 150) ÷ 150 × 100 = −33.33, which is a 33.33% decrease.

What is the percentage increase from 80 to 100?

25%. (100 − 80) ÷ 80 × 100 = 25.

What is the percentage decrease from 100 to 80?

20%. (80 − 100) ÷ 100 × 100 = −20.

Why aren't percentage increases and decreases symmetrical?

The percentage is always measured relative to the original value, and the original value changes when you reverse the direction. 100 → 150 divides by 100; 150 → 100 divides by 150.

Does a 50% increase followed by a 50% decrease cancel out?

No. 100 increased by 50% becomes 150, and 150 decreased by 50% becomes 75 — a 25% net decrease from the original value.

What is the difference between percent change and percentage points?

Percentage points measure the direct difference between two percentages. Percent change measures that difference relative to the starting percentage. A move from 5% to 6% is 1 percentage point and a 20% relative increase.

What happens if the original value is zero?

The standard percent-change formula is undefined, because it would require dividing by zero.

Is percent change the same as percent difference?

No. Percent change uses a defined original value as the denominator. Percent difference is used when neither value is naturally the baseline and typically divides by the average of the two values.