# Aggregation

Automatic aggregation is applied to most charts in InstaCharts.

You can change the aggregation function applied through the Math dropdown, located within the Y-Axis/Series dropdown on the chart toolbar.

Aggregating Impressions by Date with sum, count, average and median

Aggregation performs calculations on a set of values and returns a single value. In the video above, the values on the y-axis are changing as the aggregation is changed.

### Aggregation Functions

Below is a list of the aggregation functions you can apply to the Y Axis. In the UI, they appear next to the Y Axis under the Math dropdown.

#### Numerical Aggregation

These are mathematical functions applied to the numerical values within a column:

- **Sum** Add all values together
- **Average** Average of all values
- **Median** Middle value
- **Min** Smallest value
- **Max** Largest value

#### Non-Numerical (Text) Aggregation

These are the functions that can be applied to non-numerical values:

- **Count** Counts number of rows
- **Distinct** Count of different values
- **Valid** Counts rows with a value
- **Missing** Count of rows missing a value