Percentage Difference Calculator

This calculator shows the gap between two numbers as a percentage. The calculator first finds the difference between the two numbers. It then divides that difference by the average of the two numbers and multiplies by 100 to show the result as a percentage. Neither number is treated as the original or reference value, so the order does not matter.

How to Use the Percentage Difference Calculator

1. Enter the first number in the Value 1 box and the second number in the Value 2 box.
2. Choose how many decimal places you want in the result, from 0 to 6. The default is 2.

A few useful things to know:

• You can type numbers with commas, spaces, or a ‘$’ sign, such as 2,684 or $84. The calculator ignores those characters.
• You can also enter negative numbers, such as -3.5.

What You Will See in the Result:

• Percentage difference
• Step by step working
• Absolute difference |V1 − V2|
• Average of the two values
• Change from V1 to V2 (increase or decrease)
• Change from V2 to V1 (increase or decrease)

Example: Two phone plans cost $45 and $60 per month. Enter 45 in Value 1 and 60 in Value 2.

Difference = |45 − 60| = 15
Average = (45 + 60) ÷ 2 = 52.5
15 ÷ 52.5 × 100 ≈ 28.57%

Going from 45 to 60 is a 33.33% increase, and going from 60 to 45 is a 25.00% decrease.

What Is Percentage Difference?

Percent means ‘out of 100’. A percentage is one way to show how two numbers relate. Ratios, fractions, and decimals can show the same relationship. For example, 62% = 0.62 = 62/100.

Use percentage difference when you want to know how far apart two values are, relative to their average.

Both numbers should measure the same kind of thing in the same unit, such as the prices of one item at two stores or the test scores of two students. Comparing a store’s price with a student’s score has no meaning.

To find a percentage difference, you need two different numbers, such as 55 and 75. Their difference is 20.

To turn that 20 into a percentage, you need a reference point, called the base. Which should be the base, 55 or 75? Neither is the original value, so the fairest choice is the average of the two numbers. Here the average is 65, and 20 ÷ 65 × 100 ≈ 30.77%.

Why Do We Use the Average as the Base?

Suppose the numbers are 30 and 50, so the difference is 20.

With 30 as the base: 20 ÷ 30 = 66.67%.
With 50 as the base: 20 ÷ 50 = 40%.
With the average (40) as the base: 20 ÷ 40 = 50%.

The first two answers are very different, and neither is more correct than the other. Someone else could pick the other number as the base and get a different answer. Using the average removes that confusion.

That is why percentage difference is a non-directional comparison. It does not say that a value increased or decreased.

Percentage Difference Formula

Percentage Difference = |V1 − V2| ÷ ((V1 + V2) ÷ 2) × 100

V1 and V2: are the two values which you have to compare.

(V1 + V2) ÷ 2 is the average of the two values.

| | means absolute value. It removes the negative sign, for example |−8| = 8.

We use the absolute value because both numbers are equally important, so the difference has no direction. The minus sign is simply dropped.

If both numbers are negative, the average is negative too, so the calculator divides by the absolute value of the average. This keeps the result positive.

How to Calculate Percentage Difference Step by Step

Step 1: Find the difference. Subtract one number from the other. If the answer is negative, drop the minus sign.
Step 2: Find the average. Add both numbers and divide the sum by 2.
Step 3: Divide the difference by the average.
Step 4: Convert to a percentage. Multiply the result by 100 and add the % sign.

To convert a decimal like 0.32 to a percent, use our decimal to percent calculator.

Example: Gas Prices (With Decimals)

Gas costs $3.20 per gallon in one city and $3.80 in another.

Step 1: |3.20 − 3.80| = 0.60
Step 2: (3.20 + 3.80) ÷ 2 = 3.50
Step 3: 0.60 ÷ 3.50 = 0.1714…
Step 4: 0.1714… × 100 ≈ 17.14% (rounded to two decimal places)

To divide by hand, try our long division calculator with decimals.

Does the Order of the Numbers Matter?

Percentage difference is a “difference” not a “change”.

Example: 36 and 44.
|36 − 44| ÷ ((36 + 44) ÷ 2) × 100 = 8 ÷ 40 × 100 = 20%

Now swap the numbers: |44 − 36| ÷ ((44 + 36) ÷ 2) × 100 = 8 ÷ 40 × 100 = 20%

Both answers are the same because the absolute value removes the minus sign, and the average stays the same when the numbers swap places.

Percentage Difference vs Percentage Change

If you want to know how much a value has changed from an old value to a new value, you need percentage change, not percentage difference.

Percentage difference and percentage change both compare two numbers, but they answer different questions. Percentage difference shows how far apart two values are, using their average as the base, so the order does not matter. Percentage change shows how much a starting value has grown or shrunk, so one value is the base and the direction matters.

Take 45 and 60. Their percentage difference is 28.57% in either order. The percentage change is a 33.33% increase from 45 to 60, but a 25.00% decrease from 60 to 45.

Notice that both of these percent changes differ from 28.57%. In a percent change, one value is the base. In a percentage difference, the average of the two values is the base.

Measure	Base	Direction matters?	Use it when
Percentage difference	Average of the two values	No	Neither value is the original or the standard
Percentage change	The starting value	Yes	You have a before-and-after situation
Percent error	The accepted value	No	You compare a measurement with a known value

For a percentage increase or decrease of a single number, use our percentage calculator.

When to Use Percentage Difference (and When Not To)

When to use:

• When both values measure the same kind of thing, such as the heights of two people or the prices at two stores.
• When neither value is the ‘original’ or the standard.
• When you are comparing two independent measurements or observations, such as two lab readings, two vendor quotes, or the results of two A/B test versions.

When not to use:

• When you have an old (starting) value and a new value, use percentage change.
• If one value is a measured result and the other is a known or accepted value, use percent error.
• When you are comparing the same thing at two points in time, such as this year’s rent and last year’s rent, use percentage change.

Real-Life Uses of Percentage Difference

• Lab science: comparing two independent measurements of the same quantity.
• Quality control: checking how consistent two production batches or two machines are.
• Market research: comparing two survey results or two price quotes.
• Sports analytics: comparing two players or two teams when neither is the baseline.

Special Cases in the Calculator

• Equal values (such as 36 and 36): The result is 0%, and both change rows show “0% (no change)”.
• One value is 0 (such as 0 and 40): The percentage difference is 200%. The change from 0 shows “undefined”, because a percent change cannot be calculated from a starting value of 0.
• Exact opposites (such as 7 and −7): The result is “Undefined”, because the average is 0 and the formula would divide by zero.
• One positive and one negative value (such as 8 and −2): The calculator returns 333.33% and shows a note. The average is close to zero, so the percentage can be very large.
• Two negative values (such as −10 and −30): The result is 100%. The calculator divides by the absolute value of the average, so the result is never negative.
• Negative starting value in the change rows: The calculator divides by the absolute value of the starting number, so “increase” always means the value went up. For example, −10 to −5 is a 50.00% increase.

FAQs

Last reviewed: October 5, 2026. by the VersaCalculator team.

Sources

• Wikipedia, “Relative change”: https://en.wikipedia.org/wiki/Relative_change
• Clemson University Physics Lab Tutorials, “% Error & % Difference”: https://science.clemson.edu/physics/labs/tutorials/error/index.html
• SUNY Geneseo, Technical Report Writing Guidelines, Appendix C: https://milnepublishing.geneseo.edu/technicalreportwritingguidelines/back-matter/appendix-c-writing-tips-for-discussing-results/
• U.S. Bureau of Labor Statistics, Handbook of Methods, “Index Numbers”: https://www.bls.gov/opub/hom/topic/index-number-formulae.htm
• U.S. Bureau of Labor Statistics, Employment Projections concepts: https://www.bls.gov/emp/factsheets/concepts.htm