# Calendar heatmap

Daily calendar values with distinct zero and missing states.

Use CalendarHeatmap for daily activity over an inclusive ISO date range. Supply UTC calendar dates and keep missing values null; zero means a measured zero. Provide localized day descriptions and an accessible label for the chart and its expandable data table. The component does not fetch data.

## API

The package declarations define these public members.

| Member | Type | Kind | Required | Default | Description |
| --- | --- | --- | --- | --- | --- |
| `describeDay` | `(date: string, value: number \| null) => string` | callback | No | `undefined` | No additional description. |
| `end` | `string` | prop | Yes | - | No additional description. |
| `label` | `string` | prop | Yes | - | No additional description. |
| `locale` | `string` | prop | No | `undefined` | No additional description. |
| `start` | `string` | prop | Yes | - | No additional description. |
| `values` | `CalendarHeatmapValue[]` | prop | Yes | - | No additional description. |

## Related

- [Chart](/docs/components/chart): Accessible SVG line or area chart with tooltip and data table.
- [Sparkline](/docs/components/sparkline): Compact inline line or area trend.