Zero-Based Budget Calculator
List your income and every budget category; see the total, each category's share and how much is left to assign until your budget reaches zero.
A zero-based budget gives every dollar of income a job before the month starts, so income minus everything you assign equals exactly zero. Savings and debt payments are categories too, so reaching zero does not mean spending it all. List your categories and the calculator totals them, shows each one's share of income and tells you how much is still unassigned — or how far over you are.
How to use this tool
- Enter your monthly take-home pay and any other income.
- List one category per line with its amount at the end, such as "Rent: 1650".
- Adjust amounts until "Left to assign" reaches $0.
- Check the share column to see where most of your income goes.
Formula
Left to assign = Total income − Σ category amounts
The goal is exactly 0. A positive result is income without a job yet; a negative result means you have planned more than you will earn.
Example
With $5,200 of take-home pay and the 14 sample categories — rent $1,650, groceries $600, retirement $500 and so on — the categories add up to exactly $5,200, so $0 is left to assign. Rent is the biggest category at 31.7% of income. Raise dining out from $250 to $350 and the result turns to −$100, so another category has to give up $100.
Frequently asked questions
What if my income changes month to month?
Build the budget on a low but typical month. When extra income arrives, assign it straight away to a priority list such as the emergency fund or a debt.
Where do yearly or irregular bills go?
Give each one its own category and set aside a monthly share: a $600 yearly insurance premium becomes $50 a month, so the money is there when the bill arrives.
Does zero-based budgeting mean I spend everything?
No. Saving, investing and extra debt payments are assigned like any other category. Zero refers to unassigned money, not to your bank balance.
How is it different from the 50/30/20 rule?
The 50/30/20 rule sets three broad limits; a zero-based budget plans every category. You can combine them by checking that your needs, wants and savings categories land near 50%, 30% and 20%.
Last updated: 2026-10-30