Five numbers in a table say nothing at a glance. Five bars of different heights say everything in half a second. That's why bar graphs are everywhere.
A bar graph compares categories using rectangular bars whose lengths are proportional to the values. Great for 'which is biggest?' at a glance.
Sales by region, votes per candidate, goals per player, survey responses — anytime you compare distinct categories.
Bar graph rules
- Bars have gaps between them — categories aren't continuous.
- Start the y-axis at 0 — otherwise differences look exaggerated.
- Equal bar widths — only the length should carry meaning.
- Horizontal or vertical both fine; horizontal helps long labels.
Why is starting the y-axis at 50 instead of 0 misleading?
Bar graph vs histogram — what's the difference?
Bar graphs compare categories (gaps between bars). Histograms show distributions of a continuous variable (bars touch). Same shape, different meaning.
Truncated y-axis is the #1 way bar graphs lie. Always check where the axis starts before believing a dramatic-looking difference.
For comparing parts of a whole, a bar graph usually beats a pie chart — humans judge lengths more accurately than angles.
- Bars (with gaps) compare categories.
- Start the y-axis at 0 — or you're misleading.
- For part-of-whole comparisons, bars beat pies.