How to use the stem-and-leaf plot generator
- Paste or type your numbers, separated by spaces, commas or new lines.
- Leave the leaf unit on Choose for me, or pick one if you want a specific place value.
- In More options you can split each stem in two or five, or add a second set for a back-to-back plot.
- Read the plot sideways, check the key, and copy or print the result.
Formula
Stem = floor(rounded value / 10), leaf = rounded value mod 10, in units of the leaf unit
Rounded value = value / leaf unit, rounded half up
Median = middle value, or the mean of the two middle values
Mode = the most frequent value, if any value repeats
The leaf unit is the place value of the leaf digit. With a unit of 1 the value 62 has stem 6 and leaf 2, and with a unit of 0.1 the value 6.2 has the same stem and leaf.
16 test scores
Scores 62, 67, 71, 73, 73, 75, 78, 81, 82, 84, 84, 84, 88, 90, 93 and 95 give stems 6 to 9 with leaf unit 1. Row 6 holds the leaves 2 and 7, row 7 holds 1, 3, 3, 5 and 8, row 8 holds 1, 2, 4, 4, 4 and 8, and row 9 holds 0, 3 and 5. The key reads 6 | 2 means 62.
The median is the mean of the 8th and 9th values, 81 and 82, which is 81.5. The mode is 84 and the range is 33. Splitting each stem in two puts leaves 0 to 4 and 5 to 9 on separate rows, which spreads the plot out.
Why use a stem-and-leaf plot
A stem-and-leaf plot is a histogram that keeps the actual numbers. The rows work like the bars of a histogram, but because each leaf is a digit of a real value, you can read the data back, find the median by counting, and spot gaps and outliers. It is best for sets of up to about 100 values.
For a graphical version use the histogram maker, for quartiles use the box plot maker or the five-number summary calculator, and for grouped counts see the frequency distribution calculator.
Back-to-back plots and split stems
A back-to-back plot puts one data set on each side of a shared column of stems, which makes it easy to compare two groups, such as two classes. Leaves grow outward from the stems, so the smallest leaf is nearest the stem on both sides. Split stems divide each stem into two or five rows when too many values fall on one row.
Assumptions and limits
- Values must be zero or more. Negative numbers are not supported in the plot.
- Values with more digits than the leaf unit are rounded half up to it for the plot. The median, mode and range use your original numbers.
- Up to 500 values per set, and the plot may have up to 120 rows.
- The mode is shown only when some value repeats; otherwise the page says no value repeats.
Frequently asked questions
How do I read a stem-and-leaf plot?
Join each stem to each leaf on its row. With a key of 6 | 2 meaning 62, the row 8 | 1 2 4 4 4 8 lists the values 81, 82, 84, 84, 84 and 88. The key always tells you the place value.
What is a split stem?
A split stem uses two rows for each stem, one for leaves 0 to 4 and one for 5 to 9, or five rows for pairs of leaves. It gives more detail when a plain plot would pile many leaves on a few rows.
What is a back-to-back stem-and-leaf plot?
It compares two data sets with a shared stem column in the middle, one set's leaves running to the left and the other's to the right. It lets you compare centers and spread at a glance.
What leaf unit should I choose?
The automatic choice picks the smallest place value that keeps the plot to 25 stems or fewer. Choose a larger unit if you want a shorter plot, or a smaller unit to show more precision.