Budgets tend to allot cash for everything that we spend in a month. While a zero-sum budget is fantastic, it also helps to create a bare-bones budget at the same time. You can then compare between the two.
As personal finance blog Cashville Skyline explains, you can actually separate out your monthly expenditures into three categories: essential, negotiable and non-essential. The essential bills like rent and basic utilities make up your bare-bones budget. Everything after that can be examined separately:
My monthly expenses fall into three categories: essential, negotiable, and non-essential.
Essential expenses include: mortgage & home insurance, internet, alarm system, car insurance fund, medications, and utilities.
Negotiable expenses include: health insurance, cell phone, food & drink, personal care, and household.
Non-essential expenses include: car registration fund, savings, dentist fund, haircuts fund, Christmas fund, Cashville Skyline hosting, gas (car), gifts, and other one time expenses.
Of course, everyone's budget will be different, but calculating your own essentials-only expenses gives you a sense of how low you can really go. This can particularly come in handy if you find yourself without income for a period of time and need to cut back.