How to Calculate Percentage Increase and Decrease
A complete tutorial for finding the percentage change between two values
Try % Change CalculatorWhy This Calculation Matters
Knowing how to calculate percentage increase and decrease is essential for analyzing trends, tracking growth, and making informed decisions. Whether you're reviewing sales performance, monitoring stock prices, evaluating budget changes, or comparing year-over-year metrics, this calculation tells you by what percentage a value has changed.
This is different from applying a percentage to a value. Instead, you start with two known values—an old value and a new value—and calculate the percentage that represents the change between them.
This tutorial will walk you through the formula, show you step-by-step examples, and give you access to AnyPercent's percentage change calculator so you can verify your calculations instantly.
Understanding the Formula
The percentage change formula measures how much a value has grown or shrunk relative to its starting point. It expresses the change as a percentage of the original value.
The Formula Explained
Percentage Change = ((New Value − Old Value) ÷ Old Value) × 100
Where:
- New Value: The final or current value
- Old Value: The original or starting value
- Percentage Change: The result, showing increase (+) or decrease (−)
The formula works by finding the absolute change (New − Old), then dividing by the Old value to get the relative change, and finally multiplying by 100 to convert to a percentage.
For example, if revenue grew from $100,000 to $125,000, the percentage change is ((125,000 − 100,000) ÷ 100,000) × 100 = 25%.
You can calculate this instantly using the percentage change calculator at AnyPercent.
Step-by-Step Calculation Workflow
Follow these steps to calculate percentage increase or decrease accurately every time.
Step 1: Identify Your Values
Determine which value is the "old" (starting) value and which is the "new" (ending) value. This distinction is critical because the formula divides by the old value.
Step 2: Calculate the Absolute Change
Subtract the old value from the new value:
Change = New Value − Old Value
If the result is positive, the value increased. If negative, it decreased.
Step 3: Divide by the Old Value
Divide the change by the old value to get the relative change:
Relative Change = Change ÷ Old Value
Step 4: Convert to Percentage
Multiply the result by 100 to express it as a percentage:
Percentage Change = Relative Change × 100
Step 5: Interpret the Sign
A positive percentage indicates an increase. A negative percentage indicates a decrease. For more details on choosing between formulas, see our guide on percentage change vs percentage difference.
Calculating Percentage Increase
A percentage increase occurs when the new value is larger than the old value. The result will be positive.
Example: Revenue Growth
A company's monthly revenue increased from $80,000 to $96,000. What is the percentage increase?
Step 1: Identify values
Old Value = $80,000
New Value = $96,000
Step 2: Calculate change
Change = $96,000 − $80,000 = $16,000
Step 3: Divide by old value
$16,000 ÷ $80,000 = 0.20
Step 4: Convert to percentage
0.20 × 100 = 20%
Interpretation: Revenue increased by 20%.
Verify this calculation instantly with AnyPercent's calculator.
Calculating Percentage Decrease
A percentage decrease occurs when the new value is smaller than the old value. The result will be negative.
Example: Cost Reduction
A manufacturing cost decreased from $50,000 to $42,000. What is the percentage decrease?
Step 1: Identify values
Old Value = $50,000
New Value = $42,000
Step 2: Calculate change
Change = $42,000 − $50,000 = −$8,000
Step 3: Divide by old value
−$8,000 ÷ $50,000 = −0.16
Step 4: Convert to percentage
−0.16 × 100 = −16%
Interpretation: Cost decreased by 16% (or you can say it decreased 16%).
You can calculate decreases just as easily using the percentage change calculator.
Real-World Examples
| Scenario | Old Value | New Value | Calculation | Result |
|---|---|---|---|---|
| Stock price rise | $45 | $54 | ((54−45)/45)×100 | +20% |
| Website traffic drop | 10,000 visits | 8,500 visits | ((8500−10000)/10000)×100 | −15% |
| Salary increase | $55,000 | $58,300 | ((58300−55000)/55000)×100 | +6% |
| Inventory reduction | 2,000 units | 1,700 units | ((1700−2000)/2000)×100 | −15% |
Each example shows how the same formula adapts to different contexts. For a related formula that applies percentages to values, check out our guide on increase and decrease percentage formula.
Common Mistakes and How to Avoid Them
| Mistake | Why It Happens | How to Fix It |
|---|---|---|
| Dividing by the new value instead of the old | Confusing which value is the baseline | Always divide by the OLD (starting) value |
| Forgetting to multiply by 100 | Reporting decimal instead of percentage | Always multiply the result by 100 to convert to percentage |
| Subtracting in the wrong order | Mixing up new and old values | Always use (New − Old), not (Old − New) |
| Dividing by zero | Old value is zero | Percentage change is undefined when starting from zero; use absolute change instead |
| Ignoring the negative sign | Not recognizing decrease | A negative result means a decrease; don't drop the sign |
When to Use Percentage Change vs Other Formulas
Percentage change is the right formula when you have a clear starting point and an ending point, and you want to know how much the value changed relative to where it started.
Use percentage change when:
- Tracking growth or decline over time (sales, revenue, traffic)
- Measuring performance changes (before/after comparisons)
- Analyzing investment returns
- Evaluating the impact of business decisions
Use a different formula when:
- You want to apply a percentage to a value: Use the increase/decrease formula
- You're comparing two independent values without a clear baseline: Use the percentage difference formula
For more on choosing the right formula, see our comparison guide on percentage change vs percentage difference.
Using AnyPercent for Percentage Change
AnyPercent's percentage change calculator automates the entire process and provides additional insights:
- Enter your old and new values
- Get instant percentage change results
- See the absolute change amount
- View step-by-step formula breakdown
- Copy Excel-compatible formulas for spreadsheets
- Switch between different percentage calculations seamlessly
Related AnyPercent tools:
- Increase/Decrease Calculator: Apply a percentage change to a value
- Percentage Difference Calculator: Compare two values symmetrically
- Main Calculator Hub: Access all percentage calculation tools
Spreadsheet Formula
If you're working in Excel or Google Sheets, use this formula to calculate percentage change:
=((B1-A1)/A1)*100
Where A1 is the old value and B1 is the new value.
This formula matches exactly what AnyPercent uses, ensuring consistency between your manual calculations and automated workflows. The calculator also shows you the Excel formula for your specific values, which you can copy directly into your spreadsheet.
Conclusion
Calculating percentage increase and decrease is a fundamental skill for analyzing data and tracking change. The formula is straightforward: subtract the old value from the new value, divide by the old value, and multiply by 100. The sign of the result tells you whether the value increased or decreased.
By mastering this calculation and using tools like AnyPercent's percentage change calculator, you can quickly analyze trends, compare performance, and make data-driven decisions with confidence.
For more percentage tutorials and guides, explore our complete article library. And for related workflows, check out our guides on applying percentage changes and choosing the right formula.