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A percentage change calculator answers one of the most frequently asked questions in everyday life: how much did this value actually shift? Enter an old figure and a new figure, and the tool returns the increase or decrease as a percentage of where you started. That single number matters everywhere — whether you are checking a salary hike, tracking a stock's movement, comparing quarterly revenue, or simply working out how much a product price has moved since last month. The percentage change calculator removes the mental arithmetic and delivers a precise, verifiable result every time.
Percentage change is a relative measure. It tells you how much a quantity has grown or shrunk compared to its original value[reference:0]. The key word is "original." The change is always expressed as a percentage of the starting point, not the ending point. That distinction is why a 50% drop cannot be undone by a 50% rise — the two percentages are calculated against different bases.
The formula itself is elegantly simple: subtract the original value from the new value, divide that difference by the original value, and multiply by 100[reference:1]. A positive result signals an increase; a negative result signals a decrease. The same formula handles both directions. There is no separate equation for growth and decline[reference:2].
Written out formally:
An alternative and often shorter version is =New Value / Old Value − 1, which returns the same result with fewer brackets — useful when embedding the calculation inside a larger spreadsheet formula[reference:3].
Consider a concrete example. A company's monthly revenue was ₹4,00,000 in April and ₹5,00,000 in May. The difference is ₹1,00,000. Divide that by the original revenue (₹4,00,000) to get 0.25. Multiply by 100, and the percentage change is 25% — a 25% increase in revenue from April to May.
Now reverse the direction. If revenue had fallen from ₹5,00,000 to ₹4,00,000, the difference is −₹1,00,000. Divided by the original ₹5,00,000, that gives −0.20, or −20%. Notice that a ₹1,00,000 shift produces a 25% increase in one direction and a 20% decrease in the other. The absolute change is identical, but the percentage change differs because the base is different[reference:4].
The terms "percentage increase calculator" and "percent decrease calculator" are search terms people use when they want a quick directional answer. Mathematically, they are the same operation. The sign of the result tells you which direction the value moved.
A percentage increase means the new value exceeds the old value. A percentage decrease means the new value is lower. In both cases, the denominator is the old value. BBC Bitesize states this clearly: percentage increase or decrease is always a percentage of the original quantity[reference:5].
The practical implication is that you should never calculate a decrease by dividing the drop by the new value. If a laptop's price falls from £550 to £484, the decrease is £66. Dividing £66 by £484 gives approximately 13.6%, which is wrong. Dividing by the original £550 gives exactly 12%, which is the correct percentage decrease[reference:6].
People often use these two terms interchangeably, but they measure different things. Percentage change has a starting point. Percentage difference does not.
Percentage difference divides the absolute gap between two numbers by their average, then multiplies by 100[reference:7]. If you are comparing two values of equal standing — say, the population of two cities, or the performance of two machines — percentage difference is the right tool. If one value came before the other, percentage change is correct.
| Measure | Denominator | When to use it |
|---|---|---|
| Percentage change | Original value | Tracking change over time (prices, revenue, salary) |
| Percentage difference | Average of both values | Comparing two independent quantities |
Spreadsheet software handles percentage change with a single formula. The standard approach is to subtract the old value from the new value and divide by the old value. If the old value is in cell A2 and the new value is in cell B2, the formula is:
Excel returns a decimal such as 0.25. Press Ctrl + Shift + % to format that cell as a percentage, and it displays 25%[reference:8]. The same formula works in Google Sheets, though the percentage formatting shortcut may differ by platform.
A caution applies when the old value is negative or crosses zero. If a company moves from a loss to a profit, the percentage change calculation can produce a misleading figure. Excel's simple division formula does not handle sign changes gracefully[reference:9]. In such cases, reporting the absolute change alongside the percentage is more informative.
For a column of data, fill the formula down and apply percentage formatting to the entire column. This is the fastest route from raw numbers to a percentage change column in any spreadsheet.
The tool has applications across almost every field where numbers are tracked over time.
Sometimes you know the final value and the percentage change, but not the original. This is a reverse percentage calculation. The approach is different from a standard percentage change.
If a price increased by 20% to reach ₹1,200, the original price is 1200 / 1.20 = ₹1,000. If it decreased by 20% to reach ₹800, the original is 800 / 0.80 = ₹1,000. The formula depends on the direction: divide by (1 + percentage/100) for an increase, or (1 − percentage/100) for a decrease[reference:13].
Three errors appear repeatedly in percentage change calculations, and all three are avoidable.
The calculation is universal, but the contexts in which people use it vary by country.
In India, percentage change is central to appraisal season, where salary hikes are almost always quoted as percentages. The tool is also widely used for tracking GST-inclusive price changes and evaluating year-on-year business growth. Indian recruitment and exam notifications sometimes reference percentage changes in age or eligibility criteria, though the more common application is financial.
In the United Kingdom, percentage change appears in VAT calculations, retail pricing, and salary negotiations. The reverse percentage problem is particularly common in UK retail, where sale prices are displayed prominently but original prices are less visible.
Canadian and Australian users apply percentage change to inflation tracking, cost-of-living adjustments, and business revenue analysis. In Australia, the Reserve Bank's Inflation Calculator performs the same core operation on a national scale, adjusting dollar values for changes in the Consumer Price Index[reference:15].
| Scenario | Old Value | New Value | Percentage Change |
|---|---|---|---|
| Salary raise | 5,00,000 | 5,75,000 | +15% |
| Retail discount | 2,500 | 2,000 | −20% |
| Monthly revenue | 4,00,000 | 5,00,000 | +25% |
| Website traffic | 5,000 | 4,200 | −16% |
| Investment value | 1,20,000 | 1,50,000 | +25% |
Percentage change measures the change from a specific starting point — the original value is the denominator. Percentage difference measures the gap between two values without designating one as the starting point; it divides the difference by the average of the two numbers. Use percentage change when you know which value came first. Use percentage difference when you are comparing two quantities of equal standing.
Yes. A negative result means the value decreased. For example, if a price drops from 100 to 75, the percentage change is (75 − 100) / 100 × 100 = −25%. The minus sign tells you the direction of the change. A positive result means an increase.
Place the old value in cell A2 and the new value in cell B2. In an empty cell, type =(B2-A2)/A2 and press Enter. Excel returns a decimal. Press Ctrl+Shift+% to format it as a percentage. This works for both increases and decreases — a negative result indicates a decline.
The calculation is undefined because you cannot divide by zero. If the original value is zero and the new value is positive, the change is technically infinite — the value appeared from nothing. Standard calculators will return an error. In practical terms, reporting an absolute change is more meaningful when the base is zero.
Percentages are relative to different bases. If a value drops from 100 to 50, the decrease is 50%. To get back from 50 to 100, the increase is 50/50 = 100%. The two percentages are calculated against different original values, so they are not symmetric. This is one of the most common sources of confusion in financial reporting.
A salary hike is expressed as a percentage of your current package. If you earn 5,00,000 and receive a 15% raise, your new salary is 5,00,000 × 1.15 = 5,75,000. In India, salary hikes are typically quoted as percentages, and during appraisal season, understanding your exact percentage change helps you evaluate offers and counter-offers accurately.
Percentage points measure the arithmetic difference between two percentages. If an inflation rate moves from 2% to 3%, that is a 1 percentage point increase but a 50% percentage change. Confusing the two is one of the most common errors in media reporting and financial analysis.
If you know the final value and the percentage change, divide the final value by (1 + percentage change/100) for an increase, or (1 − percentage change/100) for a decrease. For example, if a price after a 20% increase is 120, the original was 120 / 1.20 = 100.
In sum, a percentage change calculator is more than a convenience — it is a precision tool for anyone who tracks numbers over time. Whether you are verifying a salary hike, auditing a business metric, comparing quarterly results, or simply checking how much a price has moved, the percentage change formula delivers a clear, comparable answer. Use the percentage change calculator above, enter your old and new values, and treat the output as what it is: a relative measure of movement that raw numbers alone cannot convey. A percentage difference calculator is available for cases where neither value is the designated starting point.