A stem-and-leaf plot, or stemplot, is a quick way to see the shape of a small data set without losing the actual numbers. Each value is split into a stem (its leading digits) and a leaf (its last digit), and the leaves are lined up beside their stems like a sideways bar chart. This generator builds the plot for you, picks a sensible leaf unit, and handles decimals, negative values and split stems.
How to use the stem and leaf plot generator
- Paste or type your data, separated by commas, spaces or line breaks.
- Leave Leaf unit on Automatic, or choose the place value you want the leaves to show.
- Choose One line each or Split in two for the stems.
- Read the plot below the calculator. The tape shows the key, the count, the minimum, median and maximum, and the stem and leaf units.
How a stem-and-leaf plot is built
- Choose a leaf unit, such as 1 for whole numbers or 0.1 for data with one decimal place.
- Divide each value by the leaf unit and round to a whole number.
- The last digit is the leaf; everything before it is the stem.
- List every stem from smallest to largest — including stems with no leaves — and write the leaves in increasing order.
- Add a key such as 4 | 2 = 42 so readers know the place values.
Worked example
Eighteen quiz scores: 42, 47, 51, 53, 55, 58, 61, 61, 64, 66, 67, 69, 72, 75, 78, 83, 85, 91.
With a leaf unit of 1, the tens digit is the stem and the ones digit is the leaf:
4 | 2 7 5 | 1 3 5 8 6 | 1 1 4 6 7 9 7 | 2 5 8 8 | 3 5 9 | 1 Key: 4 | 2 = 42
The plot shows a single peak in the 60s and a slightly longer tail toward the high scores. You can still read off exact values: the median is the average of the 9th and 10th leaves, 64 and 66, which is 65.
Choosing stems and leaves
Leaf unit
The automatic setting starts from the most decimal places in your data and widens the leaf unit until there are no more than about 25 stems. For prices like 12.49 and 18.75 it uses a leaf unit of 0.01 at first, but if the values span a wide range it may move to 0.1 or 1 and round. Pick a unit by hand when your textbook expects a particular layout.
Split stems
If nearly all your data fall on two or three stems, the plot looks like a few long rows and hides the shape. Splitting each stem into a 0–4 line and a 5–9 line doubles the number of rows. Some texts use five lines per stem for even more detail.
Strengths and limits
Stem-and-leaf plots work best for roughly 15 to 150 values. They keep every data point, show the distribution’s shape like a histogram, and make the median and quartiles easy to count off. For hundreds of values the rows grow too long; a histogram, such as the one in the descriptive statistics calculator, is clearer. For the five key cut points and a box plot, try the five number summary calculator.
Frequently asked questions
How do you read a stem-and-leaf plot?
Join each stem to each of its leaves using the key. With the key 4 | 2 = 42, the row 4 | 2 7 holds the values 42 and 47. The leaf unit tells you the place value of the leaf digit.
What does the leaf unit mean?
It is the place value of the last digit shown. With a leaf unit of 1, the leaf is the ones digit; with 0.1, the leaf is the tenths digit, so 3 | 7 means 3.7; with 10, the leaf is the tens digit, so 3 | 7 means 370.
What are split stems?
Each stem is listed twice, once for leaves 0–4 and once for leaves 5–9. Splitting stretches out a plot whose values crowd onto just a few stems, making the shape easier to see.
How are negative numbers shown?
Negative values get negative stems, with a separate −0 stem for values between −1 and 0 stem units, such as −2 when the leaf unit is 1. Stems run from the most negative at the top to the most positive at the bottom.
Should values be rounded or truncated?
Both conventions appear in textbooks. This generator rounds each value to the nearest leaf unit and tells you when any value was changed. If your course truncates, choose a leaf unit that matches your data's precision so no rounding is needed.