Percent Change & Year-over-Year Calculator

Worked examples: growth and decline

Suppose a small business earned 1,250 (in thousands) last year and 1,480 this year. The change is +230, the percent change is 230 ÷ 1,250 × 100 = +18.4%, and the year-over-year ratio is 118.4%. You can type the figures in whatever unit you track them in, such as thousands or millions; the percentages come out the same as long as both values use the same unit.

Now take a decline: monthly store visits fall from 8,400 to 7,350. The change is −1,050, the percent change is −12.5%, and the ratio is 87.5%. A decrease always shows a negative percent change and a ratio below 100%.

Percent change versus percentage points

When the quantity you are comparing is itself a percentage, wording matters. If a savings account rate goes from 4% to 5%, the difference is 1 percentage point. Enter 4 and 5 in this calculator, though, and it reports a percent change of +25%, because 5 is a quarter larger than 4. Both numbers are correct, but they answer different questions. In reports, use "points" for the simple difference between two rates and "percent" for relative growth, so readers do not mistake a 1-point move for a 1% move.

For seasonal figures such as retail sales or tourist numbers, compare a month with the same month a year earlier rather than with the previous month. Enter last year's figure as the old value and this year's as the new value, and seasonal swings largely cancel out.

Gains and losses are not symmetric

• After a 50% drop, you need a 100% gain, not a 50% gain, to get back to where you started, because the smaller value has to double.
• A 10% rise followed by a 10% fall leaves you at 1.1 × 0.9 = 0.99, which is 1% below the starting point.
• If a value grows from 100 to 150 over three years, the average yearly growth is not 50 ÷ 3 = 16.67%. The compound annual growth rate (CAGR), which assumes the same rate every year, is the cube root of 1.5 minus 1, or about 14.47%. This calculator compares two points in time, so keep this in mind when you turn a multi-year change into an annual figure.

When the base value is negative or very small

Imagine a company that lost 200 last year and made a profit of 100 this year. Plugging those in gives (100 − (−200)) ÷ (−200) × 100 = −150%: a negative number for what is clearly an improvement. Dividing by a negative base flips the sign, so when the starting value is below zero, analysts usually describe the change in absolute terms (an improvement of 300) or simply say the company turned profitable.

Tiny base values cause a different problem. Going from 1 to 5 is a +400% change, which sounds dramatic but may be trivial in absolute terms. When the base is small, read the difference shown alongside the percentage before drawing conclusions.