It is essentially calculated as the interest rate times the outstanding principal amount of the debt. Interest expense on the income statement represents interest accrued during the period covered by the financial statements, and not the amount of interest paid over that period.
Even though my basement bathroom cost was around $3,700, you could probably do it for just under $2,000 if you really pushed the envelope, maybe even less. I'm not going to sugarcoat the project. From a time perspective it takes awhile if you're doing it by yourself.
Typical Pricing. You'll spend at between $3,000 and $6,000 to convert a space like a garage or attic into a new bathroom. According to 2009 information from the Costhelper website, you'll spend at between $3,000 and $6,000 to convert a space like a garage or attic into a new bathroom. However, conversion costs can get as high as $25,000. If you're starting from scratch adding new square footage, you'll probably spend $25,000 to $50,000 or more for a basic 6-foot-by-8-foot room. A 10-foot-by-12-foot bathroom with higher-end amenities and fixtures like a spa bath carries an average cost of $73,145.