Use the free Histogram Maker below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
A list of numbers hides its own shape. Twenty exam scores, fifty delivery times, or a hundred heights all look like noise until you group them. A histogram groups numbers into bins, which are equal-width ranges, and draws one bar per bin showing how many values fall inside. The shape of those bars tells you at once whether the data clusters in the middle, leans to one side, has two peaks, or contains a long tail of unusual values.
The Histogram Maker builds that picture from pasted numbers. Paste a list separated by commas, spaces, or line breaks, choose how many bins to use, and press Draw histogram. The tool also reports the count, the minimum, the maximum, and the mean, so the picture and the summary sit side by side. Everything runs in your browser, and nothing you paste is uploaded or stored.
Choosing the number of bins is the one judgment call. Too few bins hide real detail: with only two bins, a class of mixed high and low scores looks like two equal blocks. Too many bins turn the picture into noise, with every bar holding one or two values and no shape visible. A good starting point is five to ten bins for a small list, and more only when you have hundreds of values. Try a few settings and watch how the shape changes; the shape that stays stable across settings is the one to trust.
A histogram is not a bar chart, and the difference matters. In a bar chart, each bar is a separate category, such as sales by city, and the bars can sit in any order. In a histogram, each bar is a range of numbers, the bars must sit in numeric order, and the width of each bar means something. Gaps between histogram bars would be wrong, because the ranges sit next to each other without breaks.
Reading the shape is a skill worth building. A bell shape, high in the middle and low at both ends, is common for measurements like heights. A shape leaning left, with a long tail to the right, is common for incomes or waiting times, where most values are small and a few are very large. Two peaks usually mean two groups mixed together, such as two classes with different teachers, and splitting the data by group will usually explain the split.
Common mistakes are easy to avoid. Keep the units consistent, because mixing centimetres and metres in one list destroys the picture. Remove text labels from the paste, since the tool reads numbers only and skips the rest. And remember that the mean can be pulled by extreme values: if the mean sits far from the tallest bar, a few very large values are doing the pulling, and the median, the middle value, may describe the typical case better.
How to make a histogram
- Paste your numbers, separated by commas, spaces, or line breaks.
- Choose the number of bins, starting with five to ten.
- Press Draw histogram and read the shape.
- Try a different bin count to check the shape is stable.
- Press Download PNG to save the image.
Frequently asked questions
How many bins should I use? Start with five to ten for a small list. Too few hide detail, too many turn the picture into noise.
What is the difference from a bar chart? Histogram bars are numeric ranges in order, not separate categories, and their widths carry meaning.
Why is the mean far from the tallest bar? A few very large values pull the mean. The tallest bar shows where most values actually sit.
Is my data uploaded? No. All binning and drawing happens in your browser.
Paste a list you already have, such as recent test scores or delivery times, and look at its shape before you summarise it with a single average. The shape often tells a story the average hides.