A histogram shows how your data is distributed across a range of values — how many values fall in each range, and whether the distribution has a clear shape or is scattered.
What is a histogram?
A histogram divides your data into equal-width intervals called bins, then draws a bar for each bin whose height represents how many values fall in that range. The result reveals the shape of your distribution: is it symmetric? skewed? does it have two peaks?
How to make a histogram
Paste your data
Open the histogram maker and enter your values — one per line, or comma-separated.
Adjust the bin count
Use the slider to set 3–50 bins. Start with the square root of your sample size as a baseline, then adjust until the shape becomes clear.
Download your chart
Save the chart as PNG for slides or PDF for sharing or printing.
Choosing the right number of bins
The number of bins dramatically changes what a histogram reveals.
| Rule | Formula | Example (n=100) |
|---|---|---|
| Square root | √n | 10 bins |
| Sturges | 1 + log₂(n) | 8 bins |
| Rice | 2 × n^(1/3) | 9 bins |
Too few bins hide the shape. Too many bins create noise. Start with √n and adjust until the shape becomes clear.
Y-axis options
- Count — raw frequency: how many values fall in each bin. The simplest and most intuitive option.
- Frequency — count ÷ total values. Bars sum to 1. Good for comparing datasets of different sizes.
- Density — frequency ÷ bin width. Good when comparing histograms that use different bin widths.
What shapes to look for
| Shape | What it means |
|---|---|
| Symmetric / bell curve | Data clusters around a central value (normal distribution) |
| Right-skewed (tail right) | Most values are low, a few are very high (e.g. incomes) |
| Left-skewed (tail left) | Most values are high, a few are very low (e.g. easy exam scores) |
| Bimodal (two peaks) | Two distinct groups in your data |
| Uniform | Values are roughly evenly spread |
When to use a histogram
- You have continuous numerical data — heights, weights, temperatures, scores
- You want to see the shape of the distribution
- You have more than ~20 values — for fewer values, try a dot plot or stem & leaf plot
Histogram vs bar chart
Histograms and bar charts look similar but represent different things:
- Histogram — continuous data, bars touch (no gap), X axis is a number line
- Bar chart — categorical data, bars have gaps, X axis has category labels
A histogram of test scores shows how many students scored in each range. A bar chart of test scores by class shows how classes compare.
FAQ
Can I make a histogram in Excel?
Yes — select your data, go to Insert → Charts → Statistical → Histogram. For faster results with more control over bin count and Y-axis type, use our free online histogram maker.
How many values do I need?
At least 10–15 for a meaningful shape. For best results, aim for 30+. With 5–10 values, a dot plot is more informative.
Why do my bars look spiky?
Too many bins. Reduce the bin count until the shape smooths out while still showing the distribution's structure.
How this guide is reviewed
This guide is maintained by the ChartsMakers Editorial Team and reviewed for statistical accuracy, product behavior, and clarity. When a guide relies on software behavior or statistical definitions, we check it against official documentation or established references. See our editorial policy.