Naming Scheme Capacity Calculator

What this generator does

Multiplies the options across the segments to get the capacity, then computes the chance of a repeat after various numbers of draws and finds the point where it passes an even chance.

How to use this tool

1. Enter how many options each segment of the name has.
2. Leave the third at zero for a two-part scheme.
3. Read the total, then read the collision threshold.
4. Add a third segment and watch the total multiply.

Understanding the controls

Segment options

How many choices each part of the name has — adjectives, nouns, numbers. Segments multiply, so a small third segment adds far more than a larger second one.

Third segment

Set it to zero for a two-part scheme, which is what most naming conventions actually use.

Common use cases

• Sizing a server or project naming convention before adopting it
• Working out when a username scheme will start colliding
• Showing why a third word is worth more than doubling the first two
• Explaining the birthday problem with a practical example
• Comparing two naming schemes by capacity and collision risk

How this generator works

The capacity is simply the product of the options, since every combination is a distinct name. The collision figure is the birthday problem: the chance that all of a set of draws are different falls surprisingly fast, and passes a half at roughly the square root of the capacity. Before display the product is recomputed from the segments, every collision chance is re-derived, the chances are confirmed to rise with the number drawn, and the threshold is confirmed to be the first count that passes an even chance.

Randomness and fairness

Nothing here is random. A set of segment sizes gives exactly one capacity and one collision curve.

For how randomness is produced across the whole site, see how Generate Random works.

Limitations and good to know

• This assumes names are drawn uniformly at random; a scheme where some options are far more popular collides sooner still.
• Draws are assumed independent, so a system that checks for duplicates before assigning has no collisions at all — at the cost of having to check.
• The collision threshold is where a repeat is more likely than not, which is well past the point where one becomes worth planning for.
• Capacity says nothing about whether the names are any good, memorable or free of unfortunate combinations.

Privacy and your data

Everything is computed in your browser and the numbers you enter are never transmitted, stored or included in analytics.