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# Read a date Explore Card and change its granularity

> Read a Mammoth date Explore Card: Columns, Timeline and List views, Earliest and Latest, day to second granularity, and the date problems a card reveals.
>
> Applies to: Roles: The transformation shortcuts need edit access to the View. Where: View › Explore › Add card › a date column

A date card shows a vertical bar chart, oldest period on the left. Each bar is a period, and its height shows how many rows fall in it; hover a bar for the exact period and value. Add one with **Add card** in the Explore panel; the shortcuts that change values need edit access to the View.

![Date Explore Card for order_date with a column chart by month, the chart type and Count menus, and Earliest and Latest values below](https://mammoth.io/docs/images/20261009_194431_DateExploreCard.webp)

## Date card views, Earliest and Latest

| View | Best for |
| --- | --- |
| **Columns** (default) | Trends and seasonality |
| **Timeline** | The same periods drawn as a line over time |
| **List** | Reading exact counts per period. **Sort by** sorts by the measure or by period in date order |

Below the chart, **Earliest** and **Latest** show the oldest and newest values with full date and time, for example `2024-01-02 12:00:00` and `2024-12-23 12:00:00`. A future date in historical data, or a Latest value much older than expected, stands out here.

![order_date card with the January 2026 bar hovered and a tooltip reading Count: 10, 83.3%, with the hint Click to select, drag across for a range](https://mammoth.io/docs/images/20261009_194456_DateCardBarTooltip.webp)

![Date card statistics showing Earliest 2024-01-02 12:00:00 and Latest 2024-12-23 12:00:00](https://mammoth.io/docs/images/20260421_160719_Statisticspanel1.webp)

## Change a date card to day, month, year or hour

Mammoth picks the period from the earliest and latest values: Year if they fall in different calendar years, Month if they fall in different months of the same year, otherwise Day. Automatic selection only ever picks **Day**, **Month** or **Year**, even for data that spans a few hours. It is recalculated when a filter narrows the dates.

1. Click the aggregation menu in the card header (it reads **Count**).
2. Choose a **Granularity**.
3. Click **Apply**.

| Granularity | Example labels | Best for |
| --- | --- | --- |
| **Day** | 01-Aug-2024 (list) or 1, 2 (chart) | Daily operations, short-term trends |
| **Month** | Jan '24 (list) or Jan-2024 (chart) | Seasonal patterns, monthly performance |
| **Year** | 2022, 2023, 2024 | Long-term trends, year-over-year |
| **Hour** | 01-Aug-2024 08:00 (list) or 8 am (chart) | Intraday patterns, shift analysis |
| **Minute** | 01-Aug-2024 08:15 (list) or 8:15 am (chart) | Process timing, high-frequency data |
| **Second** | 01-Aug-2024 08:15:00 (list) or 8:15:00 am (chart) | Real-time monitoring, event logs |

Changing granularity doesn't change your data.

![order_date card Count menu open, with Show values by COUNT, a Granularity dropdown set to Month, and Cancel and Apply buttons](https://mammoth.io/docs/images/20261009_194549_DateCardCountMenu.webp)

![Date Explore card with its More options menu open: Add to dashboard…, Copy values to clipboard, Export list as CSV and Export Image as PNG](https://mammoth.io/docs/images/20261102_explore-date-card-menu.webp)

![order_date card in list view with the Sort by menu open, showing a Count dropdown, a Descending dropdown, and Cancel and Apply buttons](https://mammoth.io/docs/images/20261009_194627_DateCardListSort.webp)

## Patterns and problems a date card reveals

| Pattern | What you see |
| --- | --- |
| Seasonality | Holiday spikes in retail, new-year bumps in subscriptions, summer slowdowns in B2B |
| Trends | Rising bars mean growth; falling bars mean decline |
| Operational rhythms | Weekday against weekend, month-end spikes, shift patterns |
| Missing periods | Absent bars where daily data should appear every day point to a collection problem |
| Future dates | A Latest value after today in historical data |
| Batch artifacts | Heavy clustering on one date, such as 90% of rows on the last day of each month |

**Worked example:** an orders card by month shows 500–700 orders a month from January to October, 2,400 in November and 3,100 in December. Double-click November and read the product category card to its right: "Gifts" dominates. For website visits over one week, switching to Hour shows peaks at 12:00–14:00 and 20:00–22:00 and a lull at 02:00–06:00.

## Troubleshooting date cards

| Symptom | Cause | Fix |
| --- | --- | --- |
| Date column appears as text, not a chart | Dates in mixed formats (for example MM/DD/YYYY and DD-MM-YYYY) | Use Convert Column Type. See [Work with dates](https://mammoth.io/docs/learn/clean-and-shape/dates/) |
| Seasonal pattern not visible | Data covers less than one full cycle, or the granularity hides it | Check Earliest and Latest; a year is needed for annual seasonality; try another granularity |
| Earliest or Latest looks wrong | Both include the time part, or the data has future or impossible dates | Read the full datetime; check for dates before the business or system existed |
| Chart changes period after filtering | Automatic granularity follows the rows currently counted | Set the granularity you want and click **Apply** |

## Related

- [Text, number and date cards](https://mammoth.io/docs/learn/explore/card-types/): Show values by, sorting and the More options menu.
- [Work with dates](https://mammoth.io/docs/learn/clean-and-shape/dates/): convert and reformat date columns.
- [Investigate a pattern with Explore Cards](https://mammoth.io/docs/learn/explore/investigate-with-explore-cards/): follow a spike into the cards to its right.

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Source: https://mammoth.io/docs/learn/explore/date-cards.md · Updated: 2026-11-08