Budget Calculator
Build a monthly budget by category and see your surplus against the 50/30/20 rule.
Inputs
Minimums on student loans, credit cards, etc.
Monthly Surplus / (Deficit)
$1,000.00
Positive means money left over; negative means you are spending more than you earn.
Total Monthly Expenses
$4,000.00
Needs
$2,750.00
Wants
$550.00
Savings & Debt
$700.00
Needs (%)
55.0%
Wants (%)
11.0%
Savings (%)
14.0%
Step by step
Monthly after-tax income
= $5,000.00
Needs
$2,750.00 (55% vs 50% target)
= $250.00 over
Wants
$550.00 (11% vs 30% target)
= $950.00 under
Savings & Debt
$700.00 (14% vs 20% target)
= $300.00 under target
Monthly surplus (unallocated)
$5,000.00 − $4,000.00
= $1,000.00
50/30/20 comparison
| Category | Actual | 50/30/20 Target | % of Income | Variance |
|---|---|---|---|---|
| Needs | $2,750.00 | $2,500.00 | 55.0% | $250.00 |
| Wants | $550.00 | $1,500.00 | 11.0% | -$950.00 |
| Savings & Debt | $700.00 | $1,000.00 | 14.0% | -$300.00 |
How it works
The 50/30/20 rule provides a quick benchmark: 50% of after-tax income to needs (housing, food, transportation, insurance, minimum debt payments), 30% to wants (dining, entertainment, hobbies), and 20% to saving and debt repayment above minimums. It's a guideline, not a law — high-cost-of-living cities may require different splits. The key output is the monthly surplus: if it's positive, you have room to accelerate savings; if negative, you need to cut spending.
Formulas
50/30/20 targets
Needs ≤ 50% of income, Wants ≤ 30%, Savings ≥ 20%
- I
- Monthly after-tax income
Monthly surplus
Surplus = Income − (Needs + Wants + Savings)
- N
- Total needs spending
- W
- Total wants spending
- S
- Total savings and extra debt payments
Frequently Asked Questions
What counts as a 'need' vs a 'want'?
Needs are non-negotiable expenses required to live and work: rent/mortgage, utilities, basic food, health insurance, minimum debt payments, and transportation to your job. Wants are lifestyle choices you could reduce if necessary: dining out, subscriptions, travel, hobbies. The line isn't always clear — a car can be a need in some cities and a want in others.
The 50% needs target feels impossible in my city. Is the rule broken?
In high-cost cities (San Francisco, NYC, London), housing alone can exceed 40% of income. Many financial planners adapt the rule to 60/20/20 or 65/20/15 when costs force it. The key is still to track all three buckets and maximise savings within your constraints.
Where should my surplus go?
First: build 3–6 months of expenses as an emergency fund. Second: maximise employer 401(k) match (it's an instant 50–100% return). Third: pay off high-interest debt (above ~6% APR). Then invest in tax-advantaged accounts (Roth IRA, maxing 401k). Only after those should you invest in taxable accounts.
Should I use gross or net income?
Net (after-tax) income. The 50/30/20 rule is meant to be applied to take-home pay — money you can actually spend. Gross income includes taxes you never see. Enter the amount deposited to your bank account each month.