Explore the Probability Lab
Flip coins and roll dice thousands of times and compare results with theory. Free, no signup, runs in your browser.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
See it in action
The Probability Lab with sample data entered and the result showing.
What is the Probability Lab?
Flip coins and roll dice thousands of times and compare results with theory. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
Probability underlies insurance, weather forecasts, medical trials, games and machine learning. Understanding randomness helps you avoid common mistakes.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Experimental results wobble in small samples but settle toward the theoretical probability.
With two dice, 7 is the most likely sum because it has the most combinations.
Each flip or roll is independent: past results do not change the next one.
Flip 1000 coins and watch the heads percentage settle.
Roll two dice 1000 times.
Track a different outcome.
Used for
Pick one to see how it fits.
Math learners
Algebra, geometry, trigonometry and calculus students, teachers preparing demonstrations, and self-learners who want to see the maths move.
Try it freeTeachers
For teachers: project the Probability Lab (Coins & Dice) on the board, let students predict the result, then run it together and test this: Roll two dice 1000 times. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
What is the law of large numbers?
As you repeat a random experiment more times, the observed frequency gets closer to the theoretical probability.
Why is 7 the most common sum of two dice?
Six of the 36 equally likely outcomes add to 7, more than any other sum.
Is the Probability Lab (Coins & Dice) free to use?
Yes. The Probability Lab (Coins & Dice) is free, needs no signup or download and runs in your web browser. It is part of the Math group of AZRS simulations.
Does the Probability Lab (Coins & Dice) work on a phone or tablet?
Yes. The Probability Lab (Coins & Dice) takes touch input as well as mouse input, so you can use its 2 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Probability Lab?
1. In the Probability Lab (Coins & Dice), use the controls to change What to roll, Track this outcome. The simulation reacts instantly. 2. In the Probability Lab (Coins & Dice), pick an option such as Coin, One die, Two dice (sum) to switch modes or load an example. 3. In the Probability Lab (Coins & Dice), press "×1", "×10", "×100", "×1000" to start, reset or change what is happening. 4. Start with this experiment: Flip 1000 coins and watch the heads percentage settle. Drag any glowing handle, object or slider with your mouse or finger and the Probability Lab (Coins & Dice) responds in real time. 5. Change one setting at a time and watch which readout moves, then compare it with this idea: Experimental results wobble in small samples but settle toward the theoretical probability.
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Try the Probability Lab now
Flip coins and roll dice thousands of times and compare results with theory. Free to use.
Try it free