How to create a heatmap

With our Datawrapper tables, you can create heatmaps like the one above. Heatmaps help your readers to see patterns in your tables. They color each cell in your table according to the underlying value. 

In this article, you'll learn first how to create the following heatmap, and then how to create the heatmap you see in the image above. Let's start with creating this heatmap first: 

1

First, create a normal table as you're used to. Upload your data, and select Table in step 3: Visualize. 

You can also style the table as you need it. Here we made the table searchable and sorted the table by the January column. 

2

Now select the numerical column(s) you want to turn into a heatmap. Then select Show as heat map in the column options below:

Note how the gradient automatically adjusts itself to the minimum and maximum number in the selected columns.

When you turn on the heatmap for your columns, you can still use all other table options. You can sort "heatmapped" columns, format them, change their column width, add a border – even add bar charts on top of the heatmap coloring.

3

You can also change the color palette: Scroll all the way down in the Refine tab to find the Heatmap section.

Here you can 

  • select another color palette. There's also a way to adjust the color palette and add your own colors. Find out how to do so in our Academy article "How to use the color palette tool".
  • choose a stepped or continuous type. Steps show all the values within a certain range with the same color. Continous assigns each value an own color on a gradient. 
  • choose the Interpolation. Read more about that topic in our Academy article "How to choose the best interpolation for your colors"
  • decide on a custom range. By default, Datawrapper sets the range between your smallest and highest value. You can decide to extend or shorten that range. Simply enter another number in the min, center or max field.  
  • Hide values in heat map columns. This way, your readers won't be able to see the underlying values anymore, so it makes sense to turn on the option Show values in tooltips instead. 
  • Show a color legend. You can find a full explanation of all the settings that appear as soon as you decide to show a color legend in our Academy article "How to customize your color legend"
4

And that's it! You know created a heatmap in our Datawrapper tables.

How to have narrow columns, but still show a header

If you want narrow columns like in the following heatmap, you need to hide the header. But you might still want to tell your readers what the data is about, like so:

To hide the header but still have this “extra header” that you can see above (“country”, “Life expectancy at birth, 1960-2019”), do the following.

1

First, when preparing the data, place the label you want to see above the heatmap in a second, otherwise empty row. Our “country” column header goes in the first column – above all the country names – and the “Life expectancy” column header goes in a second, otherwise empty column.

2

When customizing your table in the Refine tab, select Merge with empty cells at the top, and Hide header a bit further down:

3

Now select your second row under Customize rows. In our case, it’s the “country” row. Now select Move row to start of table (if it isn’t already there). If you have multiple pages, select Move row to top of page and Show row on every page instead.