Design Better Data Tables

Numerical data is read Right-To-Left; that is, we compare numbers by looking at their ones digit, then their tens, then their hundreds. Tables should keep numerical data Right-Aligned; textual data is read from Left-To-Right. If two entries start with the same letter, the second letter is used, and so on. Headers, generally, should carry whatever alignment their data has.

One easy way to keep your tables properly aligned is to keep the same number of significant figures — usually the number of digits after the decimal — consistent within each column. Significant figures is a whole rabbit hole of a topic, so I’ll keep my advice here brief: the fewer sig figs you can get by with, the better. 

Providing labels to accompany your data is crucial. These pieces of accompanying context allow a data table to be read by a wider audience, in a broader set of circumstances. 

It might sound like conventional wisdom, but giving your data table a clear and succinct title is as important as any other design decision you make. With a good title, tables are portable: they can be used in a number of different contexts, as well as cited from external sources. 

The most common label used in tables is the unit of measurement for the data; often, it’s repeated along with every single data point. Instead of repeating the label, only include it with the first data point in each column. 

Keep headers as short as possible; the design of the data table should be focused around the data itself, and long header labels can occupy a lot of visual space. 

When deciding how to style the graphic elements of a table, the goal should always be to reduce the table’s footprint without losing structural fidelity. One of the ways you can accomplish this is by using as little “ink” as possible — that is, whenever possible, choose not to style an element. 

Horizontal rules allow you to significantly reduce the vertical space occupied by long tables. Rules should be extremely light to not interfere with quick scanning. One Unsubstantiated opinion is that zebra Striping is bad.

Using colors to provide organizational context or added meaning increases the likelihood of misinterpretation or error. Tables should be Monochromatic, with graphical elements like , and .

Fivethirtyeight set their numerical data in a Typeface called Decima Mono. The Typeface is specifically designed to fit lots of data in a small space. Special thanks to Edward Tutte for his Insightful writing on design.