Percentage Increase Formula: How to Calculate Growth
By AZ Utils Editorial · · 7 min read
When a price rises, a salary goes up, or website traffic grows, you need the percentage increase formula to measure how much. It's one of the most useful — and most misused — calculations in everyday math, because the answer depends entirely on which number you treat as the starting point. This guide makes it foolproof, with the formula, worked examples and the mistakes to avoid.
It's for students, professionals, business owners and anyone tracking growth.
Key Concepts: Measuring Growth
A percentage increase expresses how much a value has grown relative to its original value. The key word is original: the increase is always measured against where you started, not where you ended.
In short: Percentage increase = the rise in value divided by the original value, times 100. Always divide by the starting figure, not the new one.
The Percentage Increase Formula
Increase % = ((New − Old) ÷ Old) × 100Equivalently, to apply an increase: New = Old × (1 + rate÷100).
Step-by-Step: Calculating a Percentage Increase
- Find the difference: New − Old.
- Divide by the original value.
- Multiply by 100.
Example: a salary rises from ₹40,000 to ₹46,000. Difference = 6,000; 6,000 ÷ 40,000 = 0.15; × 100 = 15% increase.
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Real-World Examples
Example 1 — Price rise
A product goes from ₹250 to ₹300: (50 ÷ 250) × 100 = 20% increase.
Example 2 — Traffic growth
Visitors rise from 8,000 to 10,000: (2,000 ÷ 8,000) × 100 = 25% increase.
Example 3 — Applying an increase
A ₹1,200 fee plus 8%: 1,200 × 1.08 = ₹1,296.
Common Mistakes to Avoid
- Dividing by the new value instead of the original.
- Confusing percentage increase with percentage points.
- Reversing an increase by subtracting the same percent — to undo a 20% rise, divide by 1.20, don't subtract 20%.
- Forgetting that successive increases compound, not add.
Best Practices
- Always anchor to the original value.
- State whether you mean percent or percentage points.
- For repeated increases, multiply the factors (e.g. 1.1 × 1.1 = 21%, not 20%).
- Verify with a calculator.
Frequently Asked Questions
What is the percentage increase formula?
Percentage increase = ((New - Old) / Old) x 100. Subtract the original from the new value, divide by the original, and multiply by 100.
How do I calculate a 20% increase on a number?
Multiply the number by 1.20. For example, 250 increased by 20% is 250 x 1.20 = 300.
Why do I divide by the original value?
Because a percentage increase measures growth relative to where you started. Dividing by the new value would give a different, incorrect figure.
How do I reverse a percentage increase?
Divide the new value by (1 + rate/100). To undo a 20% increase from 300: 300 / 1.20 = 250.
Do successive percentage increases add up?
No, they compound. Two 10% increases give 1.1 x 1.1 = 1.21, a 21% total rise, not 20%.
Conclusion
The percentage increase formula is simple once you remember the golden rule: divide the rise by the original value. Watch out for percentage-point confusion and compounding, and you'll measure any growth accurately. The free calculator does it instantly.
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Related Resources
- Percentage Calculator: Complete Guide — the full how-to
- Percentage Decrease Formula — the opposite calculation
- How to Calculate Percentage — the core formulas
- Profit Percentage Formula — apply it to profit
