Budget Surplus / Deficit Calculator
Add up your monthly income and spending by category to see whether you run a surplus or deficit, your savings rate, a 50/30/20 check, how each category compares with common guidelines, and how long your savings last or grow over a year.
How it works
Total income = take-home + other income · Total expenses = sum of categories + yearly costs ÷ 12 · Surplus/deficit = income − expenses · Savings rate % = surplus ÷ income × 100 · Category share = category ÷ income × 100 · 50/30/20: needs ≤ 50%, wants ≤ 30%, saving ≥ 20% · Months of savings = savings ÷ monthly expenses
A budget balances only when income beats total spending, and the surplus is the money available to save, invest or pay down debt. Expressing it as a savings rate (surplus divided by income) gives one number to track: 20% is a common healthy target, while a negative number means you are living on savings or credit. Enter your take-home pay and any other income, then fill in the categories you use. Yearly costs such as holidays or car repairs are spread over 12 months so they don’t surprise you. Planned automatic saving counts as saving, not spending, so the calculator also shows what is left after it. Each category is compared with a common guideline (housing up to 30% of take-home pay, transportation and food up to 15% each, debt payments up to 10%), and the 50/30/20 table compares your needs, wants and saving with the rule’s targets. Add the savings you already have to see how many months of expenses they cover, how long they would last at a deficit, and how long a surplus takes to build your emergency fund goal.
Worked example
On $5,000 take-home income with $1,500 housing, $500 transport, $600 food and $900 everything else, expenses total $3,500. That leaves a $1,500 surplus: a 30% savings rate, or $18,000 over a year. Housing is 1,500 ÷ 5,000 = 30% of income. On the 50/30/20 check, needs are $2,600 (52%), wants $900 (18%) and saving $1,500 (30%). With $6,000 already saved, that covers 1.7 months of expenses, and the $1,500 surplus reaches a 6-month goal of $21,000 in 10 months. If housing rose to $3,500, the $500 monthly deficit would use up the $6,000 in a year.
Sources: Monthly budget worksheet — Consumer Financial Protection Bureau
Frequently asked questions
What is a good savings rate?
Saving 20% of take-home pay is a widely used benchmark, matching the 50/30/20 budget. Higher rates speed up goals like early retirement, and any positive rate beats a deficit. Here the savings rate counts both planned saving and the surplus left over.
What if I run a deficit?
A deficit means you are funding the gap with savings or debt, which can’t last. The calculator shows the monthly cut needed to break even and, if you enter your savings, how long they would last. Start with the largest categories, usually housing and transport, since trimming them moves the number most.
Should I use gross or take-home income?
Take-home (after-tax) income is best for budgeting because it is the money actually available to spend and save. Gross income overstates what you can allocate. Guidelines here are measured against take-home pay; lenders’ debt-to-income ratios use gross pay.
What counts as needs and wants in the 50/30/20 rule?
Needs are costs you must pay: housing, utilities, transportation, groceries, insurance and healthcare, childcare and minimum debt payments. Wants are optional: entertainment, subscriptions, dining out and travel. The 20% is saving and extra debt payoff. The calculator puts the Everything else and yearly costs lines in wants, so move essentials into the named categories.
How big should my emergency fund be?
Three to six months of essential expenses is the usual advice, and more if your income is irregular or you support others. Pick a goal of 3, 6 or 12 months, enter what you have saved, and the calculator shows the target and how long your surplus takes to reach it.
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Educational estimate, not financial advice.