Do I need to install anything?

No. It runs in any modern browser, free, with no account required.

For First Responders · Elo Rating

Elo Rating for a volleyball spike

Built for first responders planning or training for real incidents. Run fast what-if scenarios for response planning and training — no software to install in the field. Simulate a volleyball spike live below — adjust the inputs and watch it respond, right in your browser.

Elo Rating SystemLive

who should win?

Player A

1600

64%

Player B

1500

36%

Controls

Presets

Player A rating

Player B rating

K-factor

The Elo system, born in chess and now everywhere from tennis to video games, turns a rating gap into a win probability. Every 400 points means a tenfold odds advantage. After each game, ratings shift by the K-factor times the surprise — beating a much stronger opponent gains far more than beating a weaker one, and an upset costs the favorite dearly.

▶ Run in Python

Data Inspector

A win probability64.0%

B win probability36.0%

A rating if win+12

A rating if loss-20

Governing equation

E_{A} = \frac{1}{1 + 1 0 ^{(1500 - 1600) /400}} = 0.640, R_{A}^{'} = R_{A} + 32 (S - E_{A})

Reading this result: A is rated +100 vs B, a 64% win chance — every 400-point gap multiplies the odds tenfold. With K=32, a win nudges A by 12 but a loss costs -20, so beating a stronger foe pays far more than beating a weaker one.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

or unlock everything with Pro →

Also for:Students Researchers Educators Engineers Hobbyists & Makers K-12 Students General version →

More with Elo Rating

Elo Rating for a basketball free throw Elo Rating for a soccer penalty Elo Rating for a baseball pitch Elo Rating for a golf putt Elo Rating for a tennis serve Elo Rating for a football field goal Elo Rating for a sprint race Elo Rating for a marathon pace

Frequently asked questions

Is this good for first responders?: Yes — this version of "Elo Rating for a volleyball spike" is framed for first responders planning or training for real incidents. Run fast what-if scenarios for response planning and training — no software to install in the field.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.