Budget Calculator

Surplus is the money nothing has claimed yet

The headline number is your monthly surplus or deficit, and what makes it worth reading is a decision most budget tools leave implicit: debt repayments and planned savings are counted as expenses here, not as things that happen to whatever is left over. A savings contribution is allocated money in exactly the way rent is — it has a job, and it is going to leave the account. Counting it as an expense gives the remaining figure a precise meaning: cash with no job yet. Your savings do not disappear by being filed that way; they still appear on their own in the savings rate, in the category breakdown, and in the charts. What the choice removes is the flattery of a surplus padded with money you have already promised somewhere else.

A deficit deserves the same plain reading in reverse. It is not a shortfall that will quietly get absorbed; it is a gap that has to be financed by something. Repeated month after month, that something is usually a card balance or an overdraft, which then returns to the budget as a debt payment line and makes the following month structurally harder than the one before it. That compounding is why the surplus line sits at the top of the results and why it carries 30 of the 100 points in the health score — more weight than any other single check on the page.

Once the number exists, the insights cards turn it into moves: up to five prioritised next steps that name the lever with the most leverage, whether that is trimming a category, lifting income, or unwinding a fixed cost. The annual view is the companion habit — it re-runs the same figures at twelve times the scale, which is where small monthly lines stop looking small and where an unassigned surplus starts looking like a decision you have been postponing rather than a comfort.

A yearly bill belongs in all twelve months, not the one it arrives in

Every amount you type is converted to a monthly equivalent before anything is added up: yearly ÷ 12, weekly × 52 ÷ 12, bi-weekly × 26 ÷ 12, and a one-time annual cost ÷ 12. Blank fields count as zero. The annual view simply runs the same arithmetic the other way, at monthly × 12. That single normalisation is what lets an 8-line income section and 65 expense lines across 9 sections be added together at all, and it is the step hand-built spreadsheets most often get wrong.

The weekly conversion is the classic error. Fifty-two weeks divided by twelve months is 4.333, not 4 — so a weekly cost multiplied by four understates that line by 0.333 ÷ 4.333, roughly 7.7% of it, every single month. Bi-weekly income has the mirror-image version: 26 fortnightly paychecks a year against 12 months works out to 2.167 per month, which means two of the year’s 26 paychecks fall outside the “two a month” mental model entirely (26 − 24 = 2). Budget bi-weekly pay as twice-monthly and you understate your annual income by exactly those two cheques, which is why the frequency selector sits on every line rather than being a single global setting.

The sinking-fund planner handles the costs that are real but not monthly — an annual insurance premium, a registration fee, a service contract, a holiday. Dividing each one by 12 turns a shock into a line item. That averaging is a deliberate modelling choice and it carries an honest cost: no actual month will look like the smooth plan. The month the premium is genuinely charged will show a large real outflow the plan has already funded eleven-twelfths of, and the eleven quiet months will look worse on paper than the bank balance feels. That is the trade a sinking fund makes — a truthful picture of the year in exchange for an untruthful picture of any single month — and it only works if the money set aside is actually left alone.

The same mechanism is how an emergency fund enters a budget. This planner treats the monthly contribution rather than the accumulated balance as part of your plan, because consistency is what builds the fund: the contribution carries 10 of the 100 health-score points and the balance carries none. A common planning range is three to six months of essential expenses, held somewhere accessible, and the useful way to read that target is in months of saving rather than as a lump. Take the worked figures in the next section: essentials there — $1,500 of housing and utilities, $600 of food, $400 of transportation and $300 of debt payments — total $2,800 a month, so three months of cover is $8,400 and six months is $16,800. At that budget’s $1,250 monthly surplus, three months of cover takes $8,400 ÷ $1,250 ≈ 6.7 months of saving and six months takes about 13.4. How long it takes is the number that changes behaviour; the target alone rarely does. What the right size is for you depends on income stability and obligations this page cannot see.

Five ratios that explain why a comfortable surplus can still be a fragile budget

Work a full month through. Take-home income $5,000; housing $1,300 plus utilities $200, giving a housing ratio of 30%; food $600; transportation $400; debt payments $300, a debt ratio of 6%; planned savings $500, a savings rate of 10%; and $450 of other spending. Total expenses come to $3,750, leaving a surplus of $1,250 a month — 25% of income, or $15,000 across the year. The potential savings rate, which adds that surplus to the planned contribution, is ($500 + $1,250) ÷ $5,000 = 35%.

On the headline that budget looks healthy. The five ratios are what tell you how much of it is actually yours to change. Expense-to-income is $3,750 ÷ $5,000 = 75%. Fixed costs — housing and utilities at $1,500 plus debt payments at $300, before essential transportation, childcare or insurance are added — already come to $1,800, or 36% of income. So of every 100 units of income, 36 are committed before the month begins, and every “just cut something” conversation has to happen inside the flexible remainder. Two households with an identical 25% surplus can be completely different animals depending on that split, which is why the fixed-cost ratio is reported separately rather than folded into expense-to-income.

The housing ratio and the debt payment ratio are the two a lender would look at, and this page shows yours against published planning guidelines directly in your results rather than applying a single rule silently in the background. That restraint is deliberate: as the sources below set out, no regulator, tax authority or standards body prescribes a correct share of income for housing or for anything else. The guideline is a position to read yourself against, not a verdict the calculator is entitled to hand down, and a 30% housing ratio in a low-cost region and in an expensive city are not the same fact.

The gap between the planned savings rate and the potential one is the whole point of the exercise. Ten per cent is what that budget has decided to save; thirty-five per cent is what it could save if the $1,250 were assigned rather than left loose. Money with no job does not sit still — it leaks into the miscellaneous line, which in this example is already $450, or 9% of income. Naming a destination for the surplus, even a boring one, is the single edit that moves the most ratios at once.

What the 100-point health score can measure, and what it has no standing to say

The budget health score is an educational 0–100 summary of six checks: surplus (30 points), savings rate (25), housing ratio (15), debt pressure (15), the emergency and sinking-fund contribution (10), and the miscellaneous buffer (5). Every threshold behind those points is published on the page itself and repeated in the Excel workbook, so you can rebuild the score by hand from your own figures and see exactly which check cost you what.

The weighting is an argument, and it is worth stating plainly rather than hiding in a formula. Surplus and savings rate together are 55 of the 100 points — more than the other four checks combined — because whether you finish the month with money, and whether any of it is deliberately kept, are the two facts every other measure depends on. Housing and debt take 15 each, 30 between them, because they are the commitments that are hardest to reverse inside a single month; a food budget can change next week, a lease cannot. The final 15 covers what makes a budget survivable rather than merely balanced: a standing contribution towards irregular and emergency costs, and a miscellaneous buffer wide enough that one unplanned expense does not invalidate the whole plan.

What the score is not: it is not a credit score, and it has no official meaning anywhere. No bureau issues it, no lender reads it, no regulator recognises it, and moving it has no effect outside this page. It is published rather than proprietary precisely because a score you cannot audit is a number you should not act on. It also cannot see the things that most determine whether a budget survives contact with a real year — how secure the income is, whether a second earner is in the household, health, dependants, and obligations that never pass through a bank account. Those absences do not make the score wrong; they make it partial, which is a different claim and a smaller one. Read the number with those limitations attached, or not at all.

Gross-income mode puts one flat rate where a progressive tax system belongs

You can start a budget from either end. If you know your take-home pay, enter it and nothing is estimated. If you only know the headline salary, gross mode estimates net as gross × (1 − the single tax and deduction rate you enter). That is a deliberate simplification, and it is the one assumption on this page most likely to be materially wrong for you.

Real payroll is not one rate. Income tax is progressive almost everywhere, with bands, thresholds and allowances that change by country and by year, sitting alongside social contributions, pension deductions and employer schemes that behave differently again. A single blended percentage can land close for a stable salary in the middle of a band, and badly off for someone near a threshold, on variable pay, or with a large pre-tax deduction. The consequence is not confined to one field: every ratio on the page divides by income, so an income figure that is wrong by a tenth makes the housing ratio, the debt ratio, the savings rate and the score wrong by the same proportion. Income errors are the most expensive errors this calculator can carry. For a sourced payroll model — US, India, UK, Canada or Australia — use the salary and take-home pay calculator and bring the net result back here.

Currency works the same way: it is presentation, not jurisdiction. Choose from INR, GBP, EUR, CAD, AUD, AED or SGD, or set a custom symbol for anything else, including NZD. What the selection changes is formatting and nothing more — no country-specific tax, benefit, legal or accounting rule is applied when you switch, and the calculator does not know which of your categories are deductible, subsidised or capped where you live. The arithmetic is identical in every currency because it is arithmetic on the numbers you supply, in a symbol you chose.

Budgets this planner is the wrong shape for

This tool models a recurring monthly household budget built from real line items. Several things people arrive looking for are a different shape of problem, and it is faster to say so than to bend them into these fields:

• A quick rule-of-thumb split. The 50/30/20 budget calculator divides income by a fixed rule and needs one number to do it. This page goes the other way: it builds a budget from your actual income, expenses, debt, savings and irregular costs, then measures what came out. Use 50/30/20 to set a target in five minutes; use this to find out what your month is really doing.
• How much house or car you can afford. Affordability runs from a loan amount, a rate and a term towards a payment, which is the opposite direction of travel from a budget. This page checks the housing and debt ratios of payments you already have. For the forward question, the mortgage calculator and the auto loan calculator each carry a dedicated affordability check.
• A wedding, a move or a renovation. These are single large events with their own internal category breakdown — venue, catering, attire — and no recurring rhythm for a monthly planner to model. You can approximate one by entering the total as a one-time annual cost, which divides it by 12, but that only answers whether your monthly budget can absorb it. It does not allocate the event itself, which is what a dedicated event-budget tool is for.
• A national budget. India’s Union “Budget 2025” or “Budget 2026” refers to the government’s annual announcement and the tax slab changes inside it, not to household planning. If that is what brought you here, the income tax calculator covers the current slabs under both the old and new regimes.

None of these are gaps in the arithmetic; they are questions with a different subject. The budget is the container the answers eventually land in, which is why each of those tools sends a number back to this one rather than replacing it.

A plan is not a record of what you actually spent

This is a planning tool, and in budgeting the distinction does more work than anywhere else. It cannot see a transaction, connect to a bank, or verify a single figure you type. Nothing is fetched: no bank feed, no cost-of-living lookup for your city, no default amounts pulled from any dataset. Every number on the results side is arithmetic on the numbers on the input side, which means the plan is exactly as honest as the month you based it on and not one point more.

That is why the order of operations matters more than the tool does. Track one real month first, from the account rather than from memory, and only then fill in these lines — the official spending tracker in the sources below exists for precisely that step. The failure mode is never the arithmetic; it is a remembered grocery figure comfortably below what the statement actually shows, repeated across a handful of spending lines until the surplus is fictional. The 65 expense lines are a prompt to jog that memory, not a checklist of everything that could apply to you, and a line you leave blank is a line the plan believes is zero.

The remaining limitations are choices rather than gaps — things this planner declines to do rather than cannot. It makes no product recommendations, offers no guarantees, and gives no professional advice of any kind. It will not tell you whether to clear debt before saving, or judge whether a category is too high for your circumstances, because both answers depend on facts about your life that never reach these fields. For serious debt, missed payments, insolvency, or any tax, legal or investment decision, the right next step is a qualified professional or a nonprofit debt counsellor, not a page of arithmetic.

Finally, a budget goes stale. Rent is renegotiated, a rate changes, a subscription renews at a higher price, income moves. Because inputs stay in your browser and nothing is stored, there is no saved profile here to quietly drift out of date — but that also means updating is something you do deliberately, by coming back and re-entering the month as it now is. Rebuilding the budget every few months, and exporting the 11-sheet workbook each time, gives you the one thing a single snapshot cannot: a record of which direction your ratios are moving.

Related calculators

Tools that build on the same money-in, money-out math:

More in Budget & Credit, or browse all calculators.

Read the guides

For more on budgeting method and the alternative quick-rule approach, see How to Build a Monthly Budget Using the 50/30/20 Rule.

Not sure what your take-home pay actually is before you budget it? See How to Estimate Take-Home Pay Without Confusing Gross and Net Income.

Sources and methodology

This planner is arithmetic on the numbers you type. Category totals, the monthly normalization of weekly and annual amounts, the surplus or deficit, and the share of income each group takes are all computed in your browser. Nothing is fetched live - no bank feed, no cost-of-living lookup for your city, and no default spending amounts pulled from any dataset.

No regulator, tax authority or standards body prescribes a correct set of budget categories, or a correct share of income for any one of them. So none of the sources below is offered as authority for a right answer. They cover the two things that do have an authority behind them: the official method for building and checking a budget, and the measured record of what households actually spend, which is the only defensible benchmark for the percentages this page shows you. Links open in a new tab.

• Monthly budget worksheet - the income-in, expenses-out structure and the surplus-or-shortfall line this planner reproduces from your own category totalsConsumer Financial Protection Bureau (CFPB) · verified 2026-09-01
• Spending tracker tool - the official method for capturing one real month of spending, which is the step that has to happen before the category lines on this page can be filled in honestlyConsumer Financial Protection Bureau (CFPB) · verified 2026-09-01
• MyMoney.gov, Spend - the US federal interagency guidance on building a spending plan and setting a maximum for each category, the framing behind the per-category monthly limits hereFinancial Literacy and Education Commission (MyMoney.gov) · verified 2026-09-01
• Consumer spending (personal consumption expenditures) - the measured national record of what US households actually spend, the benchmark for any category share this page reports back to youU.S. Bureau of Economic Analysis (BEA) · verified 2026-09-01
• Family spending in the UK - average weekly household expenditure by category, the equivalent benchmark when the currency is set to GBPOffice for National Statistics (ONS), United Kingdom · verified 2026-09-01