This is a much more subjective question than I'm sure you were hoping it was going to be, but I can lay the ground work out for what your credit needs to be for a mortgage, and what the parameters will be in some of the varying circumstances.

First of all, if your rating is over 720, you have an excellent score, and are really good to go! Lenders will be pleased to work with you, and you will have a very easy time of things. Shop around for the best interest rates, because you should really be offered something great.

People who fall between 680 and 720 are still going to have some great opportunities with low rates, not the best possible usually, but still great.

If you are above 600 but below 680 you can still generally find a good mortgage. You are going to want to emphasize your other financial strengths, however. For instance, they will ask how long you've lived at your current residence, living in the same place and working for the same employer for longer periods of time show stability, which a lender will care about. Having a healthy income and a budget that will be able to afford your monthly payments is also another good strength.

Your income to debt ratio is another important factor, so if you have high balances on credit cards, or outstanding loans, paying them down, if not completely at least partially, will help the same you look to a lender, as well as help improve your score!

With a score between 500 and 600 your home loan options are going to be much tighter. Obviously the higher you fall into this range the better. You can always apply for subprime, or bad credit, home loans but first I would suggest trying to emphasize the other factors I mentioned above and trying to find a traditional mortgage, as your interest rates will be better than they will be otherwise. Hold onto hope, and when all else fails, wait a while and try to improve your rating!

Anything below 500 will sadly be pretty much impossible to use to find a home loan.

The short answer to what credit score you need to find a mortgage is that it depends on what the lender is looking for in particular, but the above gives you more details on your options.