How to use the zero based budget calculator
- Enter your income for the month, meaning the money you will really have to spend after taxes and payroll deductions.
- List every category in the table: rent, groceries, utilities, transportation, debt payments, savings, fun and a small buffer. Use Add a category for more rows.
- Type the amount you want to give each category this month.
- Watch Left to assign. A positive number is money without a job, a negative number means you have promised more than you earn, and $0.00 means the budget is zero based.
Formula
Assigned = the sum of every category amount
Left to assign = income - assigned
Share of income = category amount / income x 100%
Amounts are added in whole cents, so the budget counts as zero based only when left to assign is exactly $0.00.
A $3,500 month with nine categories
Income is $3,500. The categories are rent $1,250, groceries $500, utilities $250, transportation $300, debt payments $400, savings $400, fun $250, giving $100 and a buffer of $50. Together they add up to $3,500, so left to assign is $0.00 and 100% of income has a job. Rent is 35.7% of income and the buffer is 1.4%.
If fun were $200 instead of $250, the categories would total $3,450 and $50 would be left to assign. You would then choose where those dollars go, such as more savings or a bigger buffer, until the number returns to zero.
What zero based budgeting means
In a zero based budget, income minus planned spending, saving and debt payments equals zero. That does not mean you spend everything. Savings, extra debt payments and a buffer are categories too, so they get a dollar amount like rent does.
The method asks you to decide where each dollar goes before the month begins, instead of finding out afterward. Some people redo the plan every month because income and bills change.
Planning tips and limits
Yearly and quarterly bills are easiest to handle by dividing them by 12 and setting that amount aside each month. The same idea works for car repairs, gifts and annual subscriptions.
This page only checks the arithmetic of the numbers you type. For a plan with needs, wants and savings groups use the budget planner. To build a cushion for surprises try the emergency fund calculator, and to see what recurring charges add up to use the subscription cost calculator.
Assumptions and limits
- Income is the amount you will actually receive in the month, after taxes and deductions.
- Every category amount is for the same month, so yearly bills have been converted first.
- Amounts are added in whole cents and nothing is rounded to make the total reach zero.
- The tool does not judge whether any amount is right for you, and it does not model taxes, interest or changing income.
Frequently asked questions
What is a zero based budget?
It is a plan in which income minus every planned expense, saving and debt payment equals zero. Each dollar is assigned a purpose before the month starts.
Does zero based mean I spend all my money?
No. Savings, investing, extra loan payments and a buffer count as categories, so money sent to them is assigned even though it is not spent on bills or shopping.
What if I cannot reach exactly zero?
A small leftover is common while you learn your spending. Give it to a category such as the buffer or savings, or carry it forward on purpose. The tool shows the exact difference so you can decide.
How do I handle irregular income?
One approach is to budget only the income you already have in hand and assign each new payment when it arrives. Another is to base the plan on your lowest likely month and treat anything extra as a bonus to assign.