Python random.randint() Function: Usage and Examples

Choose a random integer between two inclusive bounds.

What It Does and Why It Matters

random.randint(start, stop) is equivalent to randrange(start, stop + 1); both endpoints are included. It raises ValueError when the start exceeds the stop.

randint() is for pseudorandom simulations; use secrets.randbelow() for security-sensitive choices.

Pseudorandom examples are suitable for simulation and tests. Use secrets instead for tokens, passwords and authentication.

Step-by-Step Example

Start with the complete example below. Read the inputs and predict what the final print statement will show before you run it.

import random
random_generator = random.Random(42)
rolled_number = random_generator.randint(1, 6)
print(1 <= rolled_number <= 6)

How the Code Works

The imports make these standard-library tools available: random.
The name random_generator receives the value of random.Random(42). Changing this input lets you explore a different case.
The print calls display the results. Compare these results with the method’s documented return type and the input used.
The dedicated Random instance isolates the generator state from unrelated random calls. A fixed seed is useful here for repeatable demonstrations but must not be reused to generate secrets.

Expected output:

True

For the demonstrated inputs, Python displays 'True'. This result follows from the operation described above; change one input at a time to understand which rule matters.

What to Notice

Pay attention to the accepted input types, the returned value and the boundary behavior. Predict what changes if you replace the example input with an empty, zero, negative or missing value, where that value is meaningful for this operation.

If the task uses a library function, inspect its documented exceptions and return type before reusing it inside a larger function.

Where You Would Use This

Use this in calculations, data summaries, simulations or validation when the numerical assumptions match the task. Check input domains, units and precision before interpreting a result. A single example output does not prove a statistical conclusion.

Practice Exercise

Simulate ten six-sided dice rolls with a seeded Random object.

Before running your edited example, write down the result you expect. Then test at least one valid boundary or deliberately invalid value, using appropriate exception handling where necessary.

Reference: official Python documentation for the complete API contract and version notes.

Common Beginner Mistakes

Assuming the upper bound is exclusive as it is with range() or randrange().
Overlooking the documented condition: it raises ValueError when the start exceeds the stop.

Key Takeaways

Choose a random integer between two inclusive bounds.
random.randint(start, stop) is equivalent to randrange(start, stop + 1); both endpoints are included.
Simulate ten six-sided dice rolls with a seeded Random object.
Pseudorandom examples are suitable for simulation and tests. Use secrets instead for tokens, passwords and authentication.