Probability spinner v0.1.0

Press Spin.

Start from

Name each section and give it a size in parts: a section of 3 parts is three times as likely as a section of 1.

Build a spinner, spin it once or a thousand times, and watch the graph of what happened close in on what should happen.

Was this useful?

How to use it

Pick a spinner (four colors, an unfair one, a coin) or name your own sections and give each a size in parts.
Predict first: which section will come up most? How many out of 100?
Press Spin once a few times, then Spin 100 and Spin 1,000.
Compare the bars (what happened) with the dashed lines (what to expect).

Spin a fair 4-color spinner 10 times, then 1,000 times. Which graph is closer to equal?
Make a spinner with 1 red part and 3 blue parts and ask what fraction of spins should be red.
Have teams predict, then compare their prediction with the graph.
Make two spinners with the same chances but different sections and show they behave alike.
Ask why 1,000 spins match the expected chances better than 10 do.

How many sections can there be?

From 2 to 12, each from 1 to 12 parts big.

Is it really random?

Yes, each spin is drawn fresh by your browser, so results change every time.

Is anything saved or sent?

No. The spinner and its counts stay in this tab.

Nothing you do here is sent to us. Names, lists and settings stay in this browser. No sign-in, no ads. What each tool stores