What is the maximum value of a 32-bit integer, and is there an easy way to remember it?

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1

I often find myself forgetting the int max value for a 32-bit signed integer.

I know it’s a common number in programming, but I just can’t seem to memorize it.

What is the exact maximum value for an int32, and are there any helpful tricks or memory aids to recall it easily? Something simple that sticks would be really useful.

2

The int max value for a signed 32-bit integer is 2,147,483,647.

That’s because a 32-bit signed int reserves 1 bit for the sign (positive/negative), leaving 31 bits for the number itself.

So the math is: 2^31 - 1 = 2,147,483,647

One trick I use to remember it: it starts with 2.1 billion.

I just recall “2 and a bit” billion as the upper cap for int32.

Gets the job done 90% of the time when I’m eyeballing limits.

3

I kept forgetting the int max too until I started visualizing the number like this: 2-1-4-7-4-8-3-6-4-7 → read it in chunks:

  1. 2.1 (billion)

  2. 47 (my friend’s birth year)

  3. 483 (area code from a movie I like)

  4. 647 (Toronto number!)

Yeah, it’s silly, but it’s personal.

Whatever chunks you relate to will help. And just remember: int max = 2^31 - 1. That formula never changes.

4

@dharapatel.130 Here’s how I remember it when working in C, Java, or Python:

Just type this in your IDE or REPL:

python
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Edit
import sys
print(2**31 - 1)  # outputs 2147483647

This always gives the int max for a signed 32-bit int.

You’ll also find constants like INT_MAX in C/C++'s <limits.h>, or Integer.MAX_VALUE in Java both set to 2147483647.

So don’t memorize it, just remember the formula 2^31 - 1 and your tools will do the rest.