Percentage Change Calculator
Calculate the percentage increase or decrease between any two values — instantly and for free.
Tips: Use tab to move to the next field. Use shift-tab to move to the previous field. Press enter to calculate.
What is percentage change?
Percentage change measures how much a value has grown or shrunk relative to its starting point, expressed as a percentage. A positive result means an increase; a negative result means a decrease.
It is one of the most widely used calculations in everyday life — from comparing prices and tracking investment returns to measuring weight loss or monitoring business growth.
Percentage change formula
The formula for percentage change is:
A positive result indicates a percentage increase; a negative result indicates a percentage decrease.
How to calculate percentage change
- Subtract the old value from the new value to find the difference.
- Divide the difference by the old value.
- Multiply by 100 to convert to a percentage.
Example: A product cost $80 last month and costs $100 today. Difference = 100 − 80 = 20. Divided by old value: 20 ÷ 80 = 0.25. Multiplied by 100 = +25%.
Worked examples
| Scenario | Old value | New value | Change |
|---|---|---|---|
| Price increase | $80 | $100 | +25% |
| Salary cut | $60,000 | $54,000 | −10% |
| Weight loss | 90 kg | 81 kg | −10% |
| Revenue growth | $1,200,000 | $1,500,000 | +25% |
| Temperature drop | 20°C | 15°C | −25% |
| Follower increase | 2,400 | 3,000 | +25% |
| Electricity bill | £120 | £150 | +25% |
| Stock price drop | $250 | $200 | −20% |
Percentage increase vs percentage decrease
The same formula works for both increases and decreases. If the new value is higher than the old value the result is positive (increase). If the new value is lower the result is negative (decrease). You do not need a separate formula for each direction.
Note that a 50% increase followed by a 50% decrease does not return you to the starting point. A 50% increase on $100 gives $150. A 50% decrease on $150 gives $75 — not $100. This is because each percentage is calculated on a different base value.
Real-world uses
- Finance — compare investment returns, track portfolio growth, calculate interest rate changes.
- Retail — measure sales growth, compare prices between periods, evaluate discount impact.
- Health & fitness — track weight change, monitor blood pressure, measure performance improvement.
- Business — report revenue growth, measure cost changes, compare monthly or quarterly results.
- Education — compare test scores, measure class averages, track improvement over time.
Percentage change in finance and business
| Scenario | Old value | New value | Change | What it means |
|---|---|---|---|---|
| Share price | $50 | $63 | +26% | Strong annual gain |
| Mortgage rate | 3.5% | 5.25% | +50% | Significant affordability impact |
| Portfolio value | $120,000 | $108,000 | −10% | Market correction |
| Monthly website traffic | 18,400 | 22,080 | +20% | Strong organic growth |
| Quarterly revenue | £280,000 | £252,000 | −10% | Revenue decline |
| Annual salary | $65,000 | $72,800 | +12% | Above-inflation pay rise |
Month-over-month vs year-over-year
In business reporting, percentage change is nearly always quoted relative to a specific reference period. The two most common comparisons are:
- Month-over-month (MoM) — this month compared to the previous month. Useful for spotting short-term trends, but sensitive to seasonal patterns. A retailer’s sales always drop in January after December; MoM change will look alarming even when the business is healthy.
- Year-over-year (YoY) — this month compared to the same month last year. Removes seasonality, making it the preferred metric for most business KPIs, board reports, and investor communications.
| Period | Revenue | MoM change | YoY change |
|---|---|---|---|
| Dec 2024 | $120,000 | — | — |
| Jan 2025 | $72,000 | −40% (seasonal) | — |
| Jan 2026 | $79,200 | — | +10% (real growth) |
Common mistakes when interpreting percentage change
- Mixing up the base. A 50% rise followed by a 50% fall does not return to the starting point. $100 → $150 → $75. Each percentage uses a different base value.
- Confusing percentage change with percentage points. A mortgage rate rising from 3% to 4% is 1 percentage point — but a 33.3% relative increase in the rate. Both are correct; they answer different questions.
- Ignoring scale. A 10% change in a £50 product and a 10% change in a £500,000 house both read as “10%” but the cash amounts are £5 vs £50,000.
- Starting from zero. Percentage change is undefined if the old value is zero. A value rising from near-zero to anything appears as a huge percentage gain — context is essential.
- Reporting MoM for seasonal businesses. Use YoY instead to make like-for-like comparisons that eliminate seasonal effects.
Also on this site
- Percentage Calculator — find X% of Y, or what percent X is of Y
- Discount Calculator — find the sale price after any percentage off
- Tip Calculator — calculate a tip for any bill
- VAT Calculator — add or remove VAT from any price
- Percentage Increase Explained — in-depth guide with common mistakes
- Percentage vs Percentage Points — why the distinction matters
FAQ
What is the formula for percentage change?
Percentage change = ((New Value − Old Value) ÷ Old Value) × 100. A positive result means an increase; a negative result means a decrease.
How do I calculate a percentage increase?
Subtract the original value from the new value, divide by the original value, then multiply by 100. For example, an increase from 50 to 75: (75 − 50) ÷ 50 × 100 = 50%.
How do I calculate a percentage decrease?
Use the same formula. Because the new value is smaller than the old value, the result will be negative. For example, a drop from 200 to 150: (150 − 200) ÷ 200 × 100 = −25%.
What is the difference between percentage change and percentage points?
Percentage change is a relative measure. Percentage points are an absolute difference between two percentages. If a tax rate rises from 20% to 25%, that is a 5 percentage point increase, but a 25% relative increase.
Can percentage change be more than 100%?
Yes. If a value doubles it has increased by 100%. If it triples it has increased by 200%. There is no upper limit on percentage increase. Percentage decrease, however, cannot exceed −100% (which would mean the value has reached zero).
How do I reverse a percentage change?
To find the original value before a known percentage change, divide the new value by (1 + change/100). For example, if a price of $120 reflects a 20% increase, the original price was 120 ÷ 1.20 = $100.
What is a compound percentage change?
A compound change applies each percentage to the result of the previous one. For example, three consecutive 10% increases on $100: $100 → $110 → $121 → $133.10 — a total increase of 33.1%, not 30%.
How do I calculate average annual growth rate?
Divide the percentage change by the number of years. For example, a 40% increase over 4 years is approximately 10% per year on average (simple rate). For the compound annual growth rate (CAGR), use: (New ÷ Old)^(1/years) − 1.