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 swimmer's lap

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 swimmer's lap 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.

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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.

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Frequently asked questions

Is this good for first responders?: Yes — this version of "Elo Rating for a swimmer's lap" 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.