First your plan needs to allow you to take a loan. That is not a requirement, so some plans don't offer this benefit. If your plan does not allow loans, the answer is zero.

If your plan does allow loans you now need to know if it allows a longer term for purchase of a home. The most common plan design is to allow a loan up to 5 years for any purpose but up to 30 for a purchase of a home. That is a big deal when you talk about your payments, so you will want to know this.

Now to your question. The maximum loan amount set by law is 50% of your vested balance or $50,000, whichever is higher. So you could qualify for a $50,000 loan if you have a vested balance of at least $100,000. However, your plan can set a unique maximum here as well. That means you play may only allow loans for $10,000, but that would be unusual. To find out your plan's loan maximum check with your plan administrator.

Here are the steps to answer the question for you in your specific plan:
1. See if your plan allows loans.
2. See what the maximum loan amount is in your plan
3. Determine your current VESTED balance
4. See which is higher, 50% of your vested balance or the loan maximum allowed in your plan
5. The higher of these two if the answer to your question.

On a side not, even if your plan does not allow the 30 year term for home loans you can take the 5 year loan for any reason, so you could use this for the home purchase. It would just make your payments higher.

Good luck!