Budget Calculator
Build a monthly budget: enter your income and expenses to see your leftover cash and spending breakdown.
Budget Calculator — input your values
What does this financial calculator do?
This budget calculator turns your monthly income and expenses into a clear plan. It separates fixed costs — rent, utilities, groceries, transportation, insurance, debt and subscriptions — from variable spending like dining and entertainment.
The result shows your total spending, what is left over each month and your savings rate, plus a donut chart and table breaking down every category as a percentage of income. A negative leftover flags an overspending problem immediately.
Formula and variables
The savings rate is the percentage of income you are not spending.
| Symbol | Meaning |
|---|---|
| Fixed expenses | Recurring monthly costs (housing, utilities, debt) |
| Variable expenses | Discretionary spending (dining, shopping, travel) |
| Savings rate | Leftover ÷ income × 100 |
Worked example
You earn $5,000 per month with $3,060 in fixed expenses and $450 in variable expenses.
- Fixed: $1,500 + $250 + $500 + $300 + $200 + $250 + $60 = $3,060.
- Variable: $150 + $100 + $100 + $100 = $450.
- Total expenses: $3,060 + $450 = $3,510.
- Leftover: $5,000 − $3,510 = $1,490.
- Savings rate: 29.8%.
Answer: You save $1,490 per month, a 29.8% savings rate.
Tips and common mistakes
Tips
- Track every expense for a month before building the budget — most people underestimate small discretionary spending.
- Treat savings as a fixed expense: transfer it to a separate account on payday before spending.
- Review subscriptions quarterly; unused memberships quietly drain budgets.
- Use the 50/30/20 rule as a starting point and adjust to your real costs and goals.
Common mistakes to avoid
- Underestimating irregular costs like car repairs, medical bills and holiday spending, which blow up a tight budget.
- Budgeting with gross income instead of the take-home amount that actually reaches your bank account.
- Ignoring the budget for a few months and wondering why savings do not grow — review it monthly.
Budget Calculator — frequently asked questions
What is the 50/30/20 rule?
A budgeting guideline: spend 50% of after-tax income on needs, 30% on wants and save 20%. It is a flexible starting framework, not a strict law.
How much should I spend on housing?
A common guideline is no more than 30% of gross income on rent or mortgage. Lenders often use 28% to 36% ratios when approving mortgages.
What is a good savings rate?
Most planners suggest at least 10% to 20% of income. If you cannot reach it, cut variable spending first — it is easier to change than housing or debt payments.
Should I budget with gross or net income?
Use net (take-home) income for everyday budgeting, since taxes are already gone. Gross income is mainly useful for tax and retirement planning.
What if my expenses exceed my income?
Reduce variable spending, renegotiate fixed costs like insurance and subscriptions, increase income, or a combination. Continuing to overspend typically means debt.
How often should I update my budget?
Review it monthly, and rebuild it whenever income, housing or other major costs change. Small adjustments each month keep the plan realistic.