Data Labels
Data labels place category names or values directly on or near chart marks. They can reduce legend lookup, but should be used selectively so text does not overwhelm the visualization.
Use direct data labels when placing a category or value next to its mark makes the chart easier to read. Label selectively: too many labels can create clutter, and a legend may still be better for dense charts.
Key details
Important caveats
Clutter Boundary
Do not label every mark by default; direct labels should improve clarity without overcrowding the chart or colliding with other text.
Legend Boundary
Direct category labels can replace or reduce reliance on a legend when each series can be labelled clearly in place.
Further guidance
Practical Application
Use direct data labels when a small number of important values or categories can be placed near their marks without creating clutter. Prefer selective labels for key endpoints, peaks, or categories rather than labeling every mark when the chart is dense.
Purpose
Use direct labels to identify a category or value close to the relevant chart mark when that improves immediate interpretation.
Reader Check
Do the labels reduce lookup effort more than they add visual noise, and can readers still distinguish the marks without overlapping text?
Worked Example
On a line chart with twelve monthly points, label only the latest value and a notable peak if those are the points discussed in the text; do not add twelve overlapping labels when the axis already supplies the scale.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Chart typography — ONS Service Manual (opens in a new tab)Office for National Statistics · Typography and roles for chart legends, direct category labels and direct numeric data labels
- Chart elements — ONS Service Manual (opens in a new tab)Office for National Statistics · When to use chart legends versus direct labels and how legend labels/symbols are organized