For an ordinary four-digit integer, use random.randint(1000, 9999). If the value is a login or verification code that must be hard to predict, use Python’s secrets module instead. And if the first digit may be zero, treat the result as a four-character string—not a four-digit integer.
Generate a random integer from 1000 to 9999
Python’s random.randint(a, b) includes both endpoints, so this returns an integer from 1000 through 9999:
import random
number = random.randint(1000, 9999)
print(number)This is suitable for ordinary examples, games, and simulations. The Python 3.14 random documentation defines randint(a, b) as returning a value where a <= N <= b.
Generate a four-character code that can start with zero
A four-digit integer cannot begin with zero: converting 0042 to an integer produces 42. If all four positions matter, generate from 0 through 9999 and format the result as text with four digits:
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import random
code = f"{random.randrange(10_000):04d}"
print(code)The format specifier :04d pads the value with leading zeroes when needed. The result is a string, so a value such as 0042 keeps all four characters.
Use a security-focused generator for authentication codes
For an OTP, password-reset code, or other security-sensitive value, use secrets, not random. Python’s documentation warns that the pseudo-random generators in random should not be used for security purposes. The Python 3.12 secrets documentation recommends the module for cryptographically strong values and defines randbelow(n) as returning a value below the exclusive upper bound n.
For a security-sensitive four-digit integer from 1000 through 9999:
import secrets
number = secrets.randbelow(9000) + 1000
print(number)For a four-character security code that may start with zero:
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code = f"{secrets.randbelow(10_000):04d}"
print(code)These examples generate a value; they do not by themselves implement an authentication system. A real login or reset flow also needs appropriate controls for code expiry, attempt limits, delivery, and verification.
Choose the range that matches the result you need
| Requirement | Code | Possible values | Result type |
|---|---|---|---|
| Ordinary four-digit integer | random.randint(1000, 9999) |
1000–9999, inclusive | Integer |
| Ordinary four-character code, including a leading zero | f"{random.randrange(10_000):04d}" |
0000–9999 | String |
| Security-sensitive four-digit integer | secrets.randbelow(9000) + 1000 |
1000–9999 | Integer |
| Security-sensitive four-character code, including a leading zero | f"{secrets.randbelow(10_000):04d}" |
0000–9999 | String |
Keep range arguments as integers
Pass integer bounds to randrange. Since Python 3.12, it no longer automatically converts non-integer arguments, such as floats, into integers; see the version notes in the official random documentation.
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