Just remember that being self_employed means that you must also pay the self_employment tax, so include this in your calculations. The self_employment tax is double what you would pay in Medicare and Social Security taxes if you were employed.
You might choose to break down your expenses even further, between things you need to have and things you want to have. For instance, if you drive to work every day, gasoline probably counts as a need. A monthly music subscription, however, may count as a want. This difference becomes important when it’s time to make adjustments.