This is another fuzzy number, but an important one, nevertheless. The list of expenses in this calculator shows you that running a business offers a few perks. You can write off your car, your cameras, even part of your home, very legitimately. But you still need to pay for food, the part of your home your business doesn't use and school supplies for the kids. Don't count on having profit left over. You must plan to pay yourself something or the money will be spent elsewhere, on nifty new tools (or toys), travel or all-consuming personal projects. Look at your obligations and expectations, check them against your significant other's, consider economic realities and come up with a figure. If you have net profits above and beyond your salary, you can live better, save for leaner times, or buy that new, 27-frame-per-second, 30-megapixel camera and a terabyte of storage for all your huge, new images. But if you don't budget for the basics, chances are you'll come up short.