Any reputable real estate broker will "pre-qualify" you
for a mortgage before you start house-hunting. This process includes
analyzing your income, assets and present debt to estimate what you
may be able to afford on a house purchase. Mortgage brokers, or a
lender's own mortgage counselors can also calculate the same sort
of informal estimate for you.
Pre-approval makes you a strong buyer, welcomed by sellers. With
most other purchasers, sellers must tie the house up on a contract
while waiting to see if the would-be buyer can really obtain financing.
Pre-approval will also speed up the entire mortgage procedure once
you've found the house you want.