SmartCost Lab

Monthly Household Budget Calculator

Lay out your take-home pay and every regular cost — weekly, monthly or yearly — to see what's left each month, your real savings rate, and how your spending compares with the popular 50/30/20 guideline.

Last reviewed 16 October 2026 · How we build and check calculators

$

Example value. Include all regular household income after tax and deductions.

Spending and savingprivate

Example lines with made-up amounts — replace them with your own. Mark each as a need, a want, or saving/extra debt repayment.

Left over each month

$790

Savings rate 29.8% (planned saving + anything left over)

Needs
$2,465

61.6% of income · guideline 50%

Wants
$345

8.6% · guideline 30%

Saving & extra debt
$400

10.0% · guideline 20%

Spending per year
$33,720

Your budget stays in your browser. Nothing you type here is sent to us, and share links leave it out unless you tick the box.

Your split vs the 50/30/20 guideline (per month)
Show data table
Needs — you$2,465
Needs — 50%$2,000
Wants — you$345
Wants — 30%$1,200
Saving — you$400
Saving — 20%$800
Biggest items per month
Show data table
Rent or mortgage$1,400
Groceries$520
Savings$400
Eating out & fun$300
Transport$200
Energy & water$180
Phone & internet$90
Insurance$75

Your budget never leaves your device

Everything you type is calculated in your browser. We don't have accounts or a database of budgets, and share links leave out income and budget lines unless you explicitly tick the box to include them. If you share a link with figures, anyone with the link can see them.

How it works

monthly amount = weekly × 52 ÷ 12, quarterly ÷ 3, yearly ÷ 12 left over = take-home pay − (needs + wants + saving) savings rate = (planned saving + any amount left over) ÷ take-home pay

Converting weekly costs with 52 ÷ 12 (about 4.33 weeks per month) is the most common budgeting mistake to avoid: multiplying by 4 understates a $120 weekly grocery bill by about $40 a month.

The 50/30/20 guideline — useful, not a rule

The 50/30/20 split — roughly half of after-tax income on needs, 30% on wants and 20% on saving and extra debt repayment — was popularised by Elizabeth Warren and Amelia Warren Tyagi in their 2005 book All Your Worth. It's a handy starting point, but in high-cost cities housing alone can take half of take-home pay, and people paying off expensive debt may sensibly put far more than 20% towards it. Use the comparison chart to see where you differ, then decide whether that difference is a choice or a problem.

What counts as a “need” is personal. A car is a need if there's no other way to get to work; a bigger car than you need is partly a want. Classify honestly and the chart becomes far more useful.

Next steps

Sources

Results are estimates based on the figures you enter and the stated assumptions. They are not financial, tax, legal or engineering advice. Spotted a problem? Tell us.