Percentage Change Calculator - Free Online

A percentage change calculator shows how much a number grew or shrank compared with its starting value. Enter an original and a new value, and this free tool returns the percent change, the raw difference and whether the move was an increase or a decrease. It also finds what percent one number is of another and applies a percentage to any base value.

What Is Percentage Change?

Percentage change is the difference between a new value and an original value, divided by the original value and expressed as a percent. It tells you the size of a move relative to where you started, which makes numbers of different scales comparable.

The formula is: (New Value - Original Value) / |Original Value| x 100. A positive result is an increase and a negative result is a decrease. The original value is always the base, so swapping the two numbers gives a different answer.

Percentage change vs. percentage difference

These terms are often confused. Percentage change compares a new number with an earlier one and has a direction. Percentage difference compares two numbers with no "before" and "after", and usually divides by their average. This tool calculates percentage change from the original value, so use it when one number clearly came first, such as last month and this month.

What are the other two modes?

"What percent is A of B?" is a different question from "how much did it change?". The % Of mode answers the first: it divides a part by a whole. The Apply % mode goes the other direction: it takes a base value and a percentage and shows the amount, the increased total and the decreased total.

How to Use the Percentage Change Calculator

You choose one of three tabs, fill in two fields and press Calculate. Each tab answers a different question, so pick the one that matches yours.

1. Select the % Change tab to compare two values over time.
2. Type your starting number in Original Value (for example 100).
3. Type the later number in New Value (for example 125).
4. Press Calculate to see the Change, the Difference and the Direction.
5. For a share of a total, open the % Of tab, enter a Part and a Whole, and press Calculate to get the Percentage and the Ratio.
6. To work out a discount, markup or tax, open Apply %, enter a Base Value and a Percentage (%), and press Calculate.

Results appear below the button with up to four decimal places, so a value like 12.5 appears as 12.5000%. Round it yourself for reports.

Worked Examples: What the Results Look Like

Real numbers make the three modes easier to read. Here is one example for each tab.

Example 1: monthly website sessions (% Change)

Your site had 12,000 sessions in May and 15,000 in June. Enter 12000 as the Original Value and 15000 as the New Value. The calculator shows a Change of 25.0000%, a Difference of 3000.0000 and a Direction of Increase. The math is (15,000 - 12,000) / 12,000 = 0.25, or 25%.

Now try a drop. A product price falls from 80 to 68. The result is -15.0000%, a Difference of -12.0000 and a Direction of Decrease.

Example 2: a share of the total (% Of)

Out of 200 visitors, 25 signed up. Enter 25 as the Part and 200 as the Whole. You get 12.5000%, with the Ratio shown as 25 / 200. That is your signup rate.

Example 3: a discount (Apply %)

A tool costs 500 and you want to see a 20% change. Enter 500 as the Base Value and 20 as the Percentage. The calculator shows 20% of 500 is 100.0000, the increased total is 600.0000 and the decreased total is 400.0000. You see both directions at once, so you can read the sale price or the marked-up price without a second calculation.

How Do You Read and Act on the Results?

Each result card answers a specific question, and the right next step depends on the number and the context.

• Change: the percent move from the original value. Positive means growth, negative means decline.
• Difference: the raw gap in the original units, such as dollars, visits or units sold. Use it next to the percent so a big percent on a tiny base does not mislead you.
• Direction: a plain Increase or Decrease label. Zero change is labeled Increase because the check treats zero as not negative.
• Ratio: in % Of mode, this repeats your part and whole so you can confirm you typed them in the right order.

Why a 25% rise and a 25% fall do not cancel out

Percentages are always relative to the starting number. If 100 rises 25%, you get 125. A 25% drop from 125 gives 93.75, not 100. To get back to 100 from 125, the value must fall 20%. When you are checking a "recovery", run the tool in the % Change tab with the new starting point.

Percent change vs. percentage points

If a conversion rate moves from 4% to 5%, that is a 1 percentage point gain but a 25% percent change. Enter 4 and 5 in the % Change tab to confirm. Name which one you mean in any report, or readers will assume the wrong one.

Quick benchmarks

There is no universal "good" percent change. A 10% rise in monthly traffic may be strong for a mature blog and weak for a new one. Compare against your own earlier periods, the same month last year, or a stated goal rather than against a generic number.

Who Uses a Percentage Change Calculator?

Anyone comparing two figures benefits, because the percent is easier to communicate than two raw numbers. Common situations include:

• SEO and marketing reports: compare clicks, impressions, leads or revenue year over year or month over month. If you are estimating earnings, pair it with the AdSense revenue estimator, and for campaign costs use the CPM, CPC and CPA calculator.
• Pricing and shopping: check how much a price rose or fell, or use Apply % to see a sale price or a tax-inclusive total.
• Finance and business: measure growth in sales, expenses, savings or an investment balance between two dates.
• School and exams: check homework on percent increase, decrease and part-of-whole problems.
• Economics and data work: calculate the change in a price, quantity or GDP figure between two periods.

When you have a whole list of figures rather than two, the average calculator helps you find the typical value first, then compare against it.

Best Practices and Troubleshooting

Most wrong answers come from the order of the inputs or the wrong tab. Check these before you trust a surprising result.

• Put the earlier number first. Original Value is always the baseline. Swapping it with New Value turns +25% into -20%.
• Match the periods. Compare like with like, such as June to June, so seasonality does not distort the percent.
• Use the right tab. If you want "what percent is 30 of 120", use % Of, not % Change.
• Enter plain numbers. Type 15000, not 15,000 or $15k. Do not include a percent sign in the Percentage (%) field.
• Fix the "Please enter valid values." message. It appears when a field is empty or not a number, when the Original Value is 0 in % Change, or when the Whole is 0 in % Of. You cannot measure growth from zero, so describe it as "new" instead of giving a percent.
• Round for presentation. Four decimals is useful for checking, but 12.5% reads better in a report than 12.5000%.

Doing the same thing in Excel or Google Sheets

If your data lives in a spreadsheet, put the original in A2 and the new value in B2, then use =(B2-A2)/ABS(A2) and format the cell as a percentage. You can use this page to spot-check a few rows before you copy the formula down a column.

Limitations to Keep in Mind

The % Change tab measures change relative to the original value only. It does not compute a symmetric percentage difference based on the average of two numbers, and it does not chain several periods or compute compound growth rates. If the original value is negative, the calculation uses its absolute value as the base, so going from -50 to -25 is shown as a 50% increase. Interpret that carefully for things like profit and loss, where the sign has real meaning.

Results are mathematical, not advice. A big percent on a small base can look dramatic while the raw Difference stays tiny, so read both together.

Pick a tab, enter your two numbers and press Calculate to get the percent, the difference and the direction in seconds. For more utilities like this one, browse the full online calculators and utilities collection.