# What is my year over year growth?

Finds year over year growth in percent from a value last year and the same value this year, with the change in units.

- Page: https://www.acalculator.org/math/year-over-year-calculator
- JSON spec: https://www.acalculator.org/math/year-over-year-calculator.json
- Version: c40e28f133b6

## Default answer

Example with the default inputs (Last year 2,500,000, This year 2,875,000): From 2,500,000 to 2,875,000 is a change of 15% year over year.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| from | Last year | The value for the earlier period, such as last year’s sales. Not 0. |
| to | This year | The value for the same period one year later. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| growth | Year over year growth | The change from last year to this year as a percent of the size of last year’s value. |
| difference | Change | This year minus last year. |
| direction | Growth or decline | Whether the value went up, went down, or stayed the same. |

## Method

Growth = (this year − last year) ÷ |last year| × 100.

## Assumptions

- Growth is measured against the size of last year’s value, so a rise from −50 to 25 is +150%.
- Last year’s value must not be 0.
- Both values cover the same length of time, such as the same quarter one year apart.

## Worked examples

1. from = 2,500,000, to = 2,875,000 gives growth = 15%, difference = 375,000, direction = Growth. Source: OpenStax, Elementary Algebra 2e, section 3.2 Solve Percent Applications (percent increase and percent decrease: the change as a percent of the original amount; $26 to $36 is 38.5%, $3.71 to $3.64 is 1.9%), https://openstax.org/books/elementary-algebra-2e/pages/3-2-solve-percent-applications (retrieved 2026-11-01).
2. from = 26, to = 36 gives growth = 38.46%, difference = 10, direction = Growth. Source: OpenStax, Elementary Algebra 2e, section 3.2 Solve Percent Applications (percent increase and percent decrease: the change as a percent of the original amount; $26 to $36 is 38.5%, $3.71 to $3.64 is 1.9%), https://openstax.org/books/elementary-algebra-2e/pages/3-2-solve-percent-applications (retrieved 2026-11-01).
3. from = 3.71, to = 3.64 gives growth = −1.89%, difference = -0.07, direction = Decline. Source: OpenStax, Elementary Algebra 2e, section 3.2 Solve Percent Applications (percent increase and percent decrease: the change as a percent of the original amount; $26 to $36 is 38.5%, $3.71 to $3.64 is 1.9%), https://openstax.org/books/elementary-algebra-2e/pages/3-2-solve-percent-applications (retrieved 2026-11-01).
4. from = -50, to = 25 gives growth = 150%, difference = 75, direction = Growth. Source: OpenStax, Elementary Algebra 2e, section 3.2 Solve Percent Applications (percent increase and percent decrease: the change as a percent of the original amount; $26 to $36 is 38.5%, $3.71 to $3.64 is 1.9%), https://openstax.org/books/elementary-algebra-2e/pages/3-2-solve-percent-applications (retrieved 2026-11-01).
5. from = 80, to = 80 gives growth = 0%, difference = 0, direction = No change. Source: OpenStax, Elementary Algebra 2e, section 3.2 Solve Percent Applications (percent increase and percent decrease: the change as a percent of the original amount; $26 to $36 is 38.5%, $3.71 to $3.64 is 1.9%), https://openstax.org/books/elementary-algebra-2e/pages/3-2-solve-percent-applications (retrieved 2026-11-01).

## FAQ

### How do you calculate year over year growth?

Subtract last year from this year, divide by last year, and multiply by 100. Sales of $2,500,000 last year and $2,875,000 this year grew by 375,000 ÷ 2,500,000 × 100 = 15%.

### What does YoY mean?

YoY is short for year over year. It compares a period with the same period one year earlier, such as March with last March, or the third quarter with last year’s third quarter.

### Why compare with the same period last year?

It takes out regular seasonal swings. A shop that always sells more in December would look like it was growing every December if you compared it with November.

### What if the growth is negative?

The value fell. Going from 3.71 to 3.64 is a change of −0.07, which is −1.89% year over year. The page says Decline.

### What if last year was 0 or negative?

From 0 there is no growth rate, because the change would be divided by 0, so the page gives no answer. From a negative value, the change is measured against its size: −50 to 25 is a change of 75, and 75 ÷ 50 is +150%. Read that figure with care, since it means a loss turned into a profit.

### Is this the same as compound annual growth?

Over exactly one year, yes. Over several years, year over year gives one number for each pair of years, while a compound rate gives one average rate for the whole span.

## Sources

- OpenStax, Elementary Algebra 2e, section 3.2 Solve Percent Applications (percent increase and decrease are the change as a percent of the original amount; $26 to $36 is 38.5%; $3.71 to $3.64 is 1.9%). Retrieved 2026-11-01. https://openstax.org/books/elementary-algebra-2e/pages/3-2-solve-percent-applications