Histogram Maker

Histogram Maker shows how a set of numbers is spread out — marks in a class, delivery times, ages, prices. Paste the numbers, one a line (a heading on the first line is fine), or copy a column from a spreadsheet. The range is cut into bins of a tidy width — 1, 2, 2.5 or 5 times a power of ten — and a bar shows how many values fall in each, from its lower edge up to, but not including, its upper edge. The number of bins is chosen by Sturges’ rule (one more than the base-2 logarithm of the count) unless you set it; fewer bins show the overall shape, more show detail. Under the chart are the count, mean, median, sample standard deviation, lowest and highest, so you can see at a glance whether the values are symmetric (mean close to median) or skewed. Hover over a bar or use the arrow keys to read its range and count; the table lists every bin. Download as SVG or PNG, or the bins as CSV.

1. Paste the numbers, one a line, or a column of a table.
2. Give the chart a title; set the number of bins if you want.
3. Read the bins with the pointer or the arrow keys.
4. Download SVG, PNG or CSV.

• The bin width is rounded to a tidy number, so you may get one bin more or fewer than you ask for.
• One set of values at a time.
• The standard deviation is the sample one (n − 1); for a whole population it is a little smaller.
• The histogram and the figures are worked out in your browser. Your numbers are not uploaded or kept.

A histogram counts how many values fall in each range of one measure, with touching bars; a bar chart compares separate categories.

Sturges’ rule, used by default, suits up to a few hundred values. Try more bins for detail, fewer for the overall shape.

The one it starts: 60 goes in 60 to under 70, not 50 to 60.

When they are close the values are spread evenly around the middle; a mean well above the median means a few high values pull it up.