No chance < Fat chance < Slim chance

These phrases essentially mean there is little or no possibility of something working out positively, although they have slightly different nuances. I would say:

0% chance = no chance

3% chance =  fat chance

5% chance = slim chance

Native speaker like English:                                                                                                            I went for a job interview today but I have fat chance of getting it; there was no chance I could get the job; there was only a slim chance I could get the job.

Simple English: I won’t get the job.

Simple English:                                                                                                                                    Do you think the rookie will make it this year? I don’t think so!

Native speaker like English:                                                                                                      Do you think the rookie will make it this year? No chance!

Simple English:                                                                                                                                    It will be difficult for him to pass the test. We should wish him good luck!

Native speaker like English:                                                                                                      He has a slim chance of passing the test. We should wish him good luck!

We often talk about “probability” (= how much chance something is likely to happen). It is always good to have a variety of expressions to convey different meanings and nuances.

Good luck and Happy English Learning!