Budget Calculator
Add what you take home and what you spend, each in its own period. See what's left each month, how you compare with the 50/30/20 rule and how big your emergency fund should be.
Private: your budget is worked out and saved on this device only. Nothing is sent anywhere, unless you press Share, which puts your numbers in the link.
Mark each line as a need, want, saving or debt payment. This decides how the rules below count it.
Irregular and yearly costs
Costs that don't come every month, such as car servicing, gifts or a yearly subscription. Each is spread evenly: cost ÷ months apart.
Sinking funds
Saving up for something you know is coming. Monthly amount = (goal − saved so far) ÷ months until you need it. Counted as saving.
Rules, emergency fund and debt
3 to 6 is a common guide; more if your income is irregular.
Paid from your Debt payments lines. For several debts, avalanche vs snowball and exact dates, use the debt payoff calculator.
How your budget is worked out
Turn everything into a month, add up what comes in and what goes out, then compare with a rule.
- 1
Money in a month
Weekly × 52 ÷ 12Yearly ÷ 12= $4,000 in
- 2
Add what goes out
Housing $1,200+ the rest $2,190= $3,390 out
- 3
What's left
$4,000 in− $3,390 out= $610 left
- 4
Check 50/30/20
Needs 62.8% (50)Wants 12% (30)Saving 10% (20)
Read more: the formula, a worked example, the rules and tips
A budget is a plan for what comes in and what goes out over the same stretch of time. The trick is to put every amount on the same footing first, because rent may be monthly, groceries weekly and insurance yearly. This calculator turns everything into a month, then shows the result per week, 2 weeks, month or year if you prefer.
The formula
amount a month = amount × times a year ÷ 12 (a day × 365, a week × 52, 2 weeks × 26, 4 weeks × 13, a quarter × 4, a year × 1)
left over = money in − money out (below zero is a shortfall)
savings rate = savings ÷ money in × 100
50/30/20: needs vs 50% of money in, wants vs 30%, savings vs 20%
70/20/10: needs and wants vs 70%, savings vs 20%, debt payments vs 10%
zero-based: money in − everything planned = 0
emergency fund = (needs + debt payments a month) × months
irregular cost a month = cost ÷ months apart; sinking fund a month = (goal − saved) ÷ months
Worked example
Money in: take-home pay $3,800 a month + a yearly bonus of $2,400 ÷ 12 = $200, so $4,000 a month.
Needs: rent $1,200 + electricity, water and gas $150 + phone and internet $90 + groceries $120 a week × 52 ÷ 12 = $520 + fuel and fares $200 + insurance $1,200 a year ÷ 12 = $100, which comes to $2,260. Debt payments: $250. Wants: eating out $300 + subscriptions $30 + clothes and personal $150 = $480. Savings: $400.
Money out: $2,260 + $250 + $480 + $400 = $3,390. Left over: $4,000 − $3,390 = $610 a month. Savings rate: $400 ÷ $4,000 = 10%, or ($400 + $610) ÷ $4,000 = 25.25% if you save what's left.
50/30/20 (debt payments as needs): needs $2,260 + $250 = $2,510, which is 62.75% against an aim of $2,000 (50%); wants $480 = 12% against $1,200 (30%); savings $400 = 10% against $800 (20%). 70/20/10: living $2,260 + $480 = $2,740 = 68.5% against $2,800; savings 10% against $800; debt $250 = 6.25% against $400. Zero-based: $610 still needs a job.
Emergency fund: essentials $2,510 a month × 6 months = $15,060. Spending per day: $3,390 × 12 ÷ 365 = $111.45.
In Advanced, add car servicing $600 every 12 months ($50 a month, a need), gifts and holidays $1,200 every 12 months ($100, a want) and a sinking fund for a $1,500 laptop in 10 months with $300 saved: ($1,500 − $300) ÷ 10 = $120 a month. Money out becomes $3,660 and $340 is left. Essentials are now $2,560, so six months is $15,360; with $2,000 saved, $13,360 is still to go, which takes 34 months at your $400 a month of savings, or 19 months if you add the $340 left over. A $6,000 debt at 18% a year, paid at $250 a month, is cleared in about 30 months with about $1,494 of interest; adding the $340 left over ($590 a month) clears it in 12 months with about $559 of interest.
Needs, wants and savings
| Bucket | Examples |
|---|---|
| Needs | Rent or mortgage, bills, groceries, getting to work, insurance, childcare, minimum debt payments |
| Wants | Eating out, takeaways, streaming, hobbies, holidays, new clothes beyond the basics |
| Savings | Emergency fund, pension top-ups, investing, sinking funds, extra debt payments (in 50/30/20) |
| Debt payments | Credit cards, personal, car and student loans: needs for 50/30/20 unless you choose otherwise; their own 10% in 70/20/10 |
Tips
- Use your take-home pay, after tax and other deductions, not your salary before tax.
- Look at two or three months of bank statements to find costs you forget, such as subscriptions and yearly renewals.
- If your income changes month to month, budget on a low month and treat anything extra as a bonus.
- In high-cost cities needs often take more than 50%. The rules are starting points, not pass or fail.
50/30/20 was made popular by Elizabeth Warren and Amelia Warren Tyagi's book All Your Worth (2005). 70/20/10, 80/20 and zero-based budgeting are common rules of thumb, not official standards. The debt-free date is a rough guide: it treats all debts as one balance at one rate with interest charged monthly. Your budget is kept as a draft in this browser only. Checked on 11 October 2026.
Common questions
How do I make a monthly budget?
Write down what you take home after tax, then every cost, each with how often it comes round. Turn them all into a month: weekly × 52 ÷ 12, yearly ÷ 12. Take the costs from the income. In the example, $4,000 comes in and $3,390 goes out, leaving $610 a month to give a job, such as savings or paying off debt.
What is the 50/30/20 rule?
It splits take-home pay into 50% for needs (housing, bills, food, transport, insurance and minimum debt payments), 30% for wants (eating out, hobbies, shopping) and 20% for savings and extra debt payments. On $4,000 a month that is $2,000, $1,200 and $800. The example spends 62.8% on needs, 12% on wants and saves 10%.
What is the 70/20/10 rule?
It puts 70% of take-home pay towards living costs (needs and wants together), 20% into savings and 10% towards paying off debt (or giving, if you have no debt). On $4,000 that is $2,800, $800 and $400. The example spends $2,740 on living (68.5%), saves $400 (10%) and pays $250 off debt (6.3%).
What is zero-based budgeting?
You give every unit of income a job until nothing is left unassigned: income minus all planned spending, saving and debt payments equals zero. It does not mean spending everything; savings and extra debt payments count as jobs. In the example $610 a month has no job yet, so you would add it to savings, a debt or a sinking fund.
How big should my emergency fund be?
A common guide is three to six months of essential costs: needs plus debt payments. In the example the essentials are $2,510 a month, so six months comes to $15,060. In Advanced you can choose the number of months, enter what you have already saved and see how long the rest takes at your savings rate.
What is a sinking fund?
It is money you put aside each month for a known cost later, such as a new laptop, a holiday or car repairs, so it does not land as a shock. Monthly amount = (goal − saved so far) ÷ months until you need it. For a $1,500 laptop in 10 months with $300 saved, that is $1,200 ÷ 10 = $120 a month.
Related calculators
Made by Zulu Calculator, part of AlphaZulu LLC. Formulas are shown in full and rule figures are checked against official sources; see how we build calculators.