how long do you have to meditate to see results?

Meditation and its results are very individual, so it's hard to say how long you have to meditate to see results.

A key guideline to keep in mind though is to not push yourself in the beginning to meditate for longer time periods. Instead, focus on having a consistent meditation practice.

A consistent meditation practice can even consist of just 5-10 minutes of meditation per day. It really doesn't have to be longer than that, especially not in the beginning.
Pushing yourself to meditate for longer can just increase the risk of burning out and stopping the practice completely.

Having a consistent meditation practice that is long-lasting, meaning, one that you will do on a regular basis as a way of life, that is short will bring many more results and have a much bigger impact than doing a few long sessions once in a long while.

Consistency is key here.