There are two different rules of thumb for estimating ongoing maintenance costs of a home: The 1% rule and the square foot rule. These are useful in rough budgeting what you can afford in a home.
The 1% Rule#
Budget 1-4% of the home’s cost for maintenance per year. The number should be on the higher end of that range if the house is older.
The Square Footage Rule#
Budget $1 per square foot of the home. This is very broad, however, and glosses over differing costs of labor across the country, the type of finishes, etc.