Though a monthly budget is generally the most reasonable timeframe for which to set up an initial personal or household budget, there are many sources of income and expenses that do not perfectly follow a monthly schedule.For instance, you may receive a paycheck every week or two weeks, not once a month. In that case, you will want to calculate how that adds up over one month's time and write that in the appropriate row and column. You may also have certain expected or even recurring expenses that occur more or less often than monthly.
By listing all of your sources of income against all of your monthly expenditures (from required expenses like mortgage or rent payments to discretionary spending like eating out or going to the movies), you get a true picture of your personal cash flow, which will allow you to make better and more informed financial decisions. An accurate budget will also help you to answer that ever elusive question, "Can I afford it?"