Marble race

How to use this tool

1. Enter one participant per line and optionally append *count/weight.
2. Review the names, marble counts and weights, then press Start race.
3. Read the winning name and exact weight shares, and save settings JSON if you need a replay.

Combine marble counts and weights

Input and settings

Mina*3/2 Jun

Result

Four marbles; Mina has 6/7 of the winning weight and Jun 1/7

The /2 suffix gives each marble twice the winning weight; the displayed weight uses this definition.

Read the race and its probabilities

The draw first chooses a marble from the summed integer weights using rejection sampling. The race then plays that outcome, so skipping or a different display frame rate cannot change the winner. Probabilities are defined by ticket weights rather than a physics engine’s masses, friction or collisions.

Accept up to 100 names and 200 total marbles. Each name can have 1–20 marbles with integer weights of 1–100. Three marbles of weight two give that person six weight units; the result list includes both the exact numerator/denominator and a percentage.

Photo filenames and replay files

The photo option removes the extension from each filename and adds the label to the participant list. It does not inspect image pixels, location metadata or EXIF. Repeated names receive a numbered suffix; inspect the list before a broadcast because filenames may contain personal information.

A default race uses a fresh 256-bit Web Crypto seed. Downloaded JSON contains the seed, names, counts, weights and a SHA-256 check value, and can be replayed by the same algorithm version. The file cannot show whether someone deliberately chose a favorable seed, so it is not a fairness certificate.

Common questions