First-time buyers usually have the mortgage, homeowners insurance and property taxes well covered. It's the unexpected expenses from toilets that won't flush, to lawn mowers that won't start and the three gallons of paint they desperately need to fix a hideous living room, that wreck their budgets.

If you've been renting, be prepared to spend at least $100 a month on routine maintenance and improvements. Some months you'll spend a little less. Some months you'll spend three or four times more, like when the dishwasher has to be replaced.

Also make sure the heating and cooling costs don't deliver any nasty surprises. Ask the seller for a year's worth of utility bills so you'll know what to expect.

Be prepared to spend an average of a hundred dollars or more a month on minor repairs and major expenses, such as a furnace or roof that must be replaced. If you've been renting, be especially careful not to let those expenses destroy your well-planned budget.

Whether you're buying a home or refinancing an existing mortgage, we have a mortgage calculator that can help you make the right decisions.