How do I balance boys and girls in random groups?

Add ", M" or ", F" to each name and turn on "Balance gender". The number of males in each group then differs by one at most, and the same for females. If they cannot be balanced, the tool shows the counts for each group.

How do I keep people out of the same group as last time?

Save the groups with "Use these groups". Next time, turn on "Avoid last time's groupmates". After meeting the other rules, the tool keeps as few pairs from last time together as it can (sometimes not zero).

Random Group Generator: Rules, How Groups Are Made, FAQ

▶ Make groups

Group rules

Paste a list and choose the number of groups or people per group. The groups appear right away. Group sizes differ by one person at most.

Balance gender: add ", M" or ", F" after a name. The number of males in each group differs by one at most, and the same for females
Spread ★ people: add ★ to leader candidates and others. The number of ★ people in each group differs by one at most
Keep apart, keep together: one set per line. Everyone on a line goes to a different group (or the same group)
Avoid last time's groups: uses the newest groups you saved with "Use these groups"

If a rule cannot be met, the tool names it, for example "Alex and Blake are both in Group 2 (keep apart)."

How groups are made

The tool puts the rules first. The same draw number and the same input give the same groups every time.

The steps

People in a "keep together" set become one block. Blocks go into groups with free places, largest block first. The tool then tries many random swaps of blocks and keeps the order that breaks fewer rules (simulated annealing). Once every rule is met, it reduces pairs who were in the same group last time. The number of tries is set by the number of people; it does not stop on a timer.

Frequently asked questions

How do I balance boys and girls in random groups?: Add ", M" or ", F" to each name and turn on "Balance gender". The number of males in each group then differs by one at most, and the same for females. If they cannot be balanced, the tool shows the counts for each group.
How do I keep people out of the same group as last time?: Save the groups with "Use these groups". Next time, turn on "Avoid last time's groupmates". After meeting the other rules, the tool keeps as few pairs from last time together as it can (sometimes not zero).

Notes and your data

Saved data: your input is stored only in this browser (localStorage, key toban_group) and is not sent anywhere. Save to a file, load from a file, or delete it with the buttons on the page
Share links: by default, names are left out and people appear as numbers. If you include names, anyone who gets the link (including by forwarding) can read them. They go after the "#" in the link, so they are not sent to a server
Results: groups come from a random draw and fixed steps. For people who need care, set rules for them, then have a person check the final groups

Feedback box (in Japanese; you can write in English). We fix things based on what you send. We do not reply.

The site-wide about page and disclaimer and privacy policy apply to all tools.

This is an English translation of the Japanese page. If the two differ, the Japanese version prevails.