Amy Esselman explains what bullet charts are and when they are useful:
A bullet graph, or a bullet chart, is a variation of a bar chart, typically consisting of a primary bar layered on top of a secondary stack of less-prominent bars. Bullet graphs are best used for making comparisons, such as showing progress against a target or series of thresholds. For example, an organization may want to measure the current year’s sales against a goal, while contrasting it with the performance of the prior year.
Bullet graphs leverage our familiarity with bar graphs to deliver a lot of information in a compact space. If you want to display metric performance against a goal or reference point, a bullet graph offers a nicely consolidated design.
Read on for examples and alternatives.