People usually use “up to” in a non-specific informal manner. This means that it usually doesn’t matter if the upper limit number is included or not.
It really depends on the context so let’s look at some examples where “up to” is inclusive(includes the upper limit) or exclusive (doesn’t include the upper limit).
“Up to” is usually inclusive but in reality, it often doesn’t matter. If you think about the example, “you can spend up to $1,000”, you will most likely be allowed to spend exactly $1,000 or some number less than that.
In my experience “up to” is inclusive when something is possible within the range.
You can deliver the package up to the fourth of May (inclusive).
Look how tall he is, he is up to my shoulder (inclusive).
When ”up to” means something similar to until, it is often better to use until in writing.
“Up to” can have an exclusive meaning when dealing with subjects that are more precise like maths and software development.
Up to and including/not including
The best way to avoid confusion is to use “up to and including X” or “up to and not including X ”, where X is the upper limit.
This might sound a little strange in spoken English but is a good option if you are using written English and you want to be precise.