Choose the board
Start with the classic 12-row board or change the rows, peg spacing, ball size and bounciness.
Drop balls through rows of pegs and watch them build the bell curve, with the exact binomial distribution and a fitted normal curve over the slots.
Switch between real bouncing balls and the ideal 50/50 model, fast-forward thousands of balls, and read the mean, standard deviation and chi-squared test.
Loading the board…
Start with the classic 12-row board or change the rows, peg spacing, ball size and bounciness.
Press Start, drop bursts of 10 or 100, or fast-forward 1,000 or 10,000 balls.
Read the histogram against the binomial counts and the normal curve, then export a PNG, CSV or video.
Teaching probability or making a science video? Create the pictures and clips around it with WaveSpeed AI.
Make illustrations, worksheets covers and slide art for your lesson.
Turn an idea into a short explainer or intro clip.
Turn a sketch of an experiment into a 3D model.
$1 in free credits for eligible new accounts. No card needed. Generators have separate account and credit requirements. The Plinko simulator is free.
That many small random left-or-right steps add up to a predictable shape: the binomial distribution, which looks more and more like the normal (bell) curve as the number of rows grows.
Sir Francis Galton described it in 1889 as a way to show how the normal distribution arises from chance. It is also called a bean machine or quincunx, after the pattern of its pegs.
With n rows and a fair bounce at every peg, the slot number follows a binomial distribution with mean n/2 and standard deviation √n/2. The simulator draws these expected counts over the slots so you can compare.
Yes. In physics mode every ball bounces off the pegs under gravity, and like a real board its curve comes out a little wider than the ideal binomial. Switch to the ideal 50/50 model for exact coin flips.
Yes, completely free with no sign-up and no watermark. It runs in the browser on laptops, classroom computers and tablets.
Binomial & normal curves · Thousands of balls in seconds · PNG, CSV & video