I was using a tool that suggest how I can increase my credit score. One thing was that it said my credit limit is "low." But it didn't say what "low" is.
What is considered a low credit limit?
Your credit limit is a secret function of your score, income-to-debit ratio and the expected default rate, at the least, for your profile.
This means the median credit limit changes based on each group of the above variables, and since we don't know what your profile is, it's not possible to guess a number.
However, anything below $500 is a low credit limit as high risk profiles (no/low income, low score) seem to have that limit in my personal experience.
If you are earning money and paying taxes on it, and you have a 600+ score, I guess a reasonable credit limit is $2500, and anything below that is low.
f1Student is right in that it is a function of your credit history and related factors. Credit Karma has a feature where it aggregates card statistics from all users. I pulled up the numbers for one of the more popular cards right now. While it doesn't directly answer your question, it should give you an idea of the distribution of credit limits.