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# Turn columns into rows with Unpivot in Mammoth

> Use Unpivot in Mammoth to turn wide columns like Jan_Sales, Feb_Sales and Mar_Sales into rows, with a label column for the old headers and a value column.
>
> Applies to: Where: View › Describe your transformation › Reshape, Group & Pivot › Unpivot

**Unpivot** turns a wide table into a long one: column headers become row values. Use it when you have one column per period or category, such as Jan_Sales, Feb_Sales and Mar_Sales, and need one Month column and one Sales column. Most grouping, joining and analysis works best on the long layout.

![Unpivot panel with Dimensions and Name columns selected, label column title Product, value column title Size, and an example](https://mammoth.io/docs/images/20260417_125251_Unpivotconfigurationpanel1.webp)

## Unpivot columns into rows

1. In your View, click **Describe your transformation**, then **Reshape, Group & Pivot** › **Unpivot**.
2. In **Select columns to be transposed**, pick the columns to turn into rows. Once you pick one, only columns of the same type are offered.
3. In **"Label" column title**, name the new column that will hold the old column headers.
4. In **"Value" column title**, name the new column that will hold the old cell values.
5. If the columns are numbers or dates, set **Format**. For numbers, set the number format of the value column. For dates, click **Choose date format** and pick one.
6. Click **Apply**.

All other columns are kept and repeated on each new row. The two new names must differ from each other and from existing columns.

**Example:** a View has `store`, `Jan_Sales`, `Feb_Sales` and `Mar_Sales`. Select the three sales columns, name the label column `Month` and the value column `Sales`, and click **Apply**. Each store now has three rows, one per month.

## Troubleshooting Unpivot

| Symptom | Cause | Fix |
| --- | --- | --- |
| "A column with same name already exists. Try another value" (Unpivot) | A new column name is already used | Choose a different label or value column title |
| "The new value column does not carry over the meaning of the columns you stack (an ID, a currency or a percentage). It starts as a plain column." (Unpivot) | The stacked columns were marked as an ID, currency or percentage | Add a **Convert Column Type** step after the Unpivot to restore the meaning |

## Related

- [Group, pivot and unpivot data](https://mammoth.io/docs/learn/clean-and-shape/group-and-pivot/): summarise the long table.
- [Column types, IDs, currency and percentages](https://mammoth.io/docs/learn/clean-and-shape/column-types/): how a column gets its meaning.
- [Convert text to dates and numbers](https://mammoth.io/docs/learn/clean-and-shape/convert-column-type/): restore a type after unpivoting.
- [Combine datasets](https://mammoth.io/docs/learn/organise/combine-datasets/): other ways to bring data together.

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Source: https://mammoth.io/docs/learn/clean-and-shape/unpivot.md · Updated: 2026-11-08