While looking for a home to purchase, I had to build my own spreadsheets to figure out if I could really AFFORD it. Not just the mortgage, not just the taxes, rather the whole enchalada. These are calculations you should not be doing on the back of a napkin...hence the name Napkin Real Estate. Simply add in the required fields and tap 'Calculate' at the bottom. It will show you if you will be 'Cash Flow Positive' at the end of each month. You can even email the data to yourself. Best of Luck.