Monthly Take-Home Pay (after taxes)
£5,000.00
- Needs
- £2,500.00
- Wants
- £1,500.00
- Savings
- £1,000.00
£2,500.00
50%£1,500.00
30%£1,000.00
20%A split on paper is not a budget yet
Turn these three numbers into real categories in iBudget and track what you actually spend against them.
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Needs
Example breakdown:
- Housing
- £1,250.00
- Utilities
- £375.00
- Groceries
- £500.00
- Insurance
- £250.00
- Transportation
- £125.00
Wants
Example breakdown:
- Dining Out
- £450.00
- Entertainment
- £375.00
- Shopping
- £375.00
- Subscriptions
- £300.00
Savings
Example breakdown:
- Emergency Fund
- £400.00
- Retirement
- £400.00
- Other Goals
- £200.00
How this calculator works
Three multiplications and one rebalancing rule. Here is exactly what the tool above does with the number you type in.
The formula
needs = I x (n / 100) | wants = I x (w / 100) | savings = I x (s / 100) where n + w + s = 100- I
- Monthly take-home pay, exactly as you type it. Parsed as a decimal number; anything blank or non-numeric is treated as zero.
- n
- Needs percentage. Defaults to 50, adjustable between 20 and 80 in whole percentage points.
- w
- Wants percentage. Defaults to 30, adjustable between 10 and 50 in whole percentage points.
- s
- Savings percentage. Defaults to 20, adjustable between 10 and 50 in whole percentage points.
Move any one slider and the tool sets that value, then splits the remaining 100 - x between the other two buckets in proportion to the ratio they currently hold, rounding to whole percentage points and clamping each to its own range. The three percentages therefore always sum to exactly 100. Amounts are calculated at full precision and rounded only for display, to two decimal places in every currency except the yen, which is shown in whole units.
The arithmetic is deliberately shallow. The calculator takes the one number you type in, multiplies it by each of the three percentages, and shows the results. There is no tax engine, no bank connection, no lookup of local rents and no assumption about your household size. The number you enter is the only input, and the three figures that come out are that input sliced three ways.
That makes the input the part that matters. The field is labelled take-home pay for a reason: 50/30/20 was designed around the money that actually arrives, because the tax you never see is not money you can allocate. If you paste in your gross salary, every bucket will be too large by exactly your effective tax rate, and the savings target in particular will look far more achievable than it is.
The sliders are where the tool does something slightly more interesting than multiplication. Move any one of them and the other two are recalculated rather than left to drift, so the three always total exactly 100%. The remainder is divided between the two buckets you did not touch in proportion to the ratio they already had, rounded to whole percentage points, then clamped to each slider's own range. Drag needs up and wants and savings both give ground, roughly in the proportion you had them.
Amounts are computed at full floating-point precision and only rounded when they are displayed, by the currency formatter — to two decimal places in every currency the tool offers except the yen, which is shown in whole units. So the three bucket figures on screen will always add back to your income, give or take a cent of display rounding. The percentages themselves are whole numbers only — there is no 22.5% savings setting.
A worked example
One run through the arithmetic, in US dollars, on a household taking home $5,200 a month.
Suppose you take home $5,200 a month
Worked example- Monthly take-home pay (I)
- $5,200.00
- Needs at 50% = 5,200 x 0.50
- $2,600.00
- Wants at 30% = 5,200 x 0.30
- $1,560.00
- Savings at 20% = 5,200 x 0.20
- $1,040.00
- Check: 2,600 + 1,560 + 1,040
- $5,200.00
Now drag the needs slider to 60%. The tool has 40 percentage points left and splits them in the ratio the untouched buckets already held (savings 20 out of the 50 points shared by wants and savings, so 0.4 of the remainder): savings becomes 16% and wants 24%. On the same $5,200 that is $3,120 of needs, $1,248 of wants and $832 of savings — the savings bucket has lost $208 a month, or $2,496 over a year, to a ten-point rise in fixed costs. That trade is the single most useful thing the sliders show you.
How to read your result
What a workable split looks like, how far the averages sit from 50/30/20, and what to change first.
The output is a target, not a diagnosis. It becomes useful the moment you put it next to what you already spend, which the calculator cannot see. Pull up last month's statement, sort every line into the same three buckets, and compare. The gap between the two is the entire value of the exercise.
The needs bucket is the one that usually breaks first, and national spending data explains why. Housing takes 33.4% of the average US household budget and transportation another 17.0% — together, the whole 50% allocation before a single grocery shop. UK households show the same shape: housing, fuel and power at 18% of weekly spending and transport at 14%, and the ONS books mortgage interest and Council Tax outside the housing line, so the real housing burden is higher than 18% suggests. If your needs land at 55-65%, you are in normal territory rather than failing.
The savings bucket is where the 20% looks most ambitious against reality. The US personal saving rate was 2.7% of disposable income in June 2026, and on the OECD's net measure households saved 5.7% in the US and 4.7% in the UK across 2024. Both are national aggregates rather than surveys of what individual families put aside, and they are not directly comparable with each other — but the direction is unambiguous. Hitting 20% would put you far above the national average in every English-speaking market.
Three things to do with the result. First, if your real needs exceed the needs figure, the fix is almost always structural — housing, transport or insurance — rather than a smaller coffee habit. Second, if your wants bucket is the one running over, that is the easiest and least painful place to claw back a few points. Third, whatever the split, make the savings transfer automatic and dated for the day you are paid, because a bucket that depends on what is left at the end of the month reliably ends up empty.
33.4%
Housing, as a share of the average US household budget
2024. On its own that is two thirds of a 50% needs bucket, before food, insurance or a car. The BLS surveys "consumer units", which are close to but not identical with households.
Source: US Bureau of Labor Statistics, Consumer Expenditure Surveys 2024
17.0%
Transportation, as a share of the average US household budget
2024. Housing and transportation together come to 50.4% of spending — the entire needs allocation, before a single grocery run.
Source: US Bureau of Labor Statistics, Consumer Expenditure Surveys 2024
£118.40 a week
UK spending on housing, fuel and power
18% of weekly spending in the year to March 2025 — and it excludes mortgage interest and Council Tax, which the ONS books under other expenditure items, so the true housing burden is higher.
Source: ONS, Family spending in the UK, April 2024 to March 2025
£96.40 a week
UK transport spending
14% of the weekly total and the second largest line. From the Living Costs and Food Survey, about 5,000 responding households, so detailed categories carry wide uncertainty.
Source: ONS, Family spending in the UK, April 2024 to March 2025
2.7%
US personal saving rate, June 2026
A national accounts aggregate covering the whole household sector, not a survey of families — so read it as the national picture rather than as what a typical household manages.
Source: US Bureau of Economic Analysis, Personal Income and Outlays, June 2026
5.7% US / 4.7% UK
Net household saving rate, 2024
Canada 5.1%, Australia 6.1%, Sweden highest in the OECD at 16.3%. This is the OECD net measure, after depreciation and as a share of net disposable income; it is not comparable with the gross saving ratios national agencies publish.
Source: OECD, National Accounts at a Glance (measure B8NS1M)
What this calculator does not account for
Every simplification the tool makes, stated plainly, so you know how much weight the number can carry.
It does no tax calculation at all
There is no gross-to-net conversion anywhere in the component. It cannot tell whether you entered take-home pay or gross salary, and it will happily produce a confident-looking budget from the wrong number.
It never sees a single one of your actual expenses
The tool does not ask what you spend and cannot check your split against reality. The example breakdowns under each bucket — housing at half of needs, dining out at 30% of wants, and so on — are fixed illustrative fractions written into the code. They are not derived from your data and they are not survey averages.
Monthly figures only
There is one input and it is a month. Weekly, fortnightly, four-weekly and annual pay all have to be converted by hand before you type them in, and irregular income has to be flattened to a single number you choose.
No inflation, interest or investment growth
The savings figure is a monthly deposit target and nothing more. It is not projected forward, not compounded and not adjusted for rising prices, so the amount shown is in today's money in every sense.
Whole percentage points, inside fixed bounds
Needs are limited to 20-80% and wants and savings to 10-50% each, in steps of one percentage point. Splits outside those ranges are unreachable, and because the three are forced to total exactly 100% you cannot use the tool to model a month where you spend more than you earn.
It does not know how you are paid into your pension
Contributions deducted before payday are already missing from the income you enter, so they never appear in the 20%. Contributions you make yourself afterwards do. The calculator draws no distinction, which means two people saving identically can produce very different-looking results.
No debt logic
Nothing in the tool looks at balances, interest rates or payoff order. Putting extra repayment in the savings bucket is a convention this page recommends, not a calculation the component performs — for the actual arithmetic of clearing a balance, use the debt payoff tools.
Rounding is visible if you look for it
When the sliders redistribute, the recalculated percentages are rounded to whole numbers, which can shift a bucket by up to half a point from a clean proportional split. Displayed amounts are rounded by the currency formatter — two decimal places in most currencies, whole units in yen — so the three buckets can appear to miss your income total by a cent.
The currency is cosmetic
The symbol comes from your browser locale or a saved preference. Nothing is converted — enter 5,000 and you get 5,000 of whatever currency is being displayed.
None of this makes the 50/30/20 split useless. It makes it a first pass. The rule is good at telling you whether your fixed costs have quietly swallowed the room you needed for everything else, and bad at telling you what to do about it — that part needs your real categories and your real transactions.
Frequently asked questions
What is the 50/30/20 budget rule?
It is a budgeting framework popularised by Elizabeth Warren and Amelia Warren Tyagi in the book All Your Worth. You put 50% of your after-tax income towards needs, 30% towards wants and 20% towards savings and extra debt repayment. Its appeal is that it fits on a napkin: three buckets, no spreadsheet, no forty-line category list.
Should I enter gross or net income?
Net — the money that actually lands in your account after tax. This calculator has no tax engine of any kind, so if you type your gross salary every bucket comes out inflated by whatever your tax rate is. In the US that means pay after federal and state income tax and FICA; in the UK it means pay after Income Tax and National Insurance.
What actually counts as a need rather than a want?
A need is something that has real consequences if you stop paying it: rent or mortgage, utilities, groceries, insurance, transport to work, and the minimum payment on any debt. A want is the upgraded version of a need or a purely optional one — the restaurant meal rather than the groceries, the streaming bundle, the holiday. The honest test is whether skipping it for three months would damage your health, housing or employment.
My needs are already 65% of my income. Is the rule broken?
No, but it is telling you something. Housing alone takes 33.4% of the average US household budget and transportation another 17.0%, so a 50% needs bucket is genuinely tight before you have bought food. Drag the needs slider to where you actually are and see what is left: the point of the exercise is to find out how much room the other two buckets have, not to pretend you fit a template.
Where do 401(k) or workplace pension contributions belong?
If the contribution comes out before your pay hits your account, it is already excluded from the figure you typed in and does not belong in the 20% again. If you pay into a retirement account manually from your current account, it goes in the savings bucket. The calculator cannot tell which case you are in, so decide once and be consistent.
Is debt repayment savings or needs?
The convention is that minimum payments are needs, because missing them has consequences, and anything above the minimum is savings, because it is building your net worth by reducing what you owe. The calculator does not enforce this or look at your interest rates. If you are carrying a balance at a high rate, clearing it usually beats adding to a low-interest savings account, but that is a judgement about your own numbers rather than something the tool decides.
Is 20% enough to save?
It depends entirely on when you started, what you already hold and what you are saving for, and no single percentage answers that for everyone. What the 20% figure is good for is being unambiguous: it stops saving being whatever happens to be left at the end of the month. If you want to test whether a given monthly amount reaches a specific target by a specific date, use the savings goal or compound interest calculators instead.
Should a couple run one 50/30/20 or two?
One, on combined take-home pay, if you share the bills — otherwise the person paying rent looks reckless and the person who does not looks disciplined, when nothing about the household has changed. Split the buckets by household, then decide separately how much personal spending money each of you takes out of the wants bucket. Running two separate budgets on the same shared expenses double-counts them.
What if my income is irregular or freelance?
Run the calculator on your lowest realistic month rather than your average, so the needs bucket is covered even in a bad month. Anything above that baseline in a good month can go straight to savings, which naturally overshoots 20% in busy periods and covers the quiet ones. The calculator itself only understands one flat monthly figure — it has no concept of a range or a seasonal pattern.
Why are the sliders capped at 20-80% and 10-50%?
The bounds stop the three buckets producing nonsense: needs can move between 20% and 80%, wants and savings between 10% and 50% each. Whenever you move one slider the other two are recalculated so the total is always exactly 100%. It means some splits are unreachable in the tool — 90/5/5, for example — which is a deliberate constraint rather than a bug.
Does the calculator store or send my income figure?
No. Everything runs in your browser as you type, nothing is submitted anywhere and nothing is saved when you close the tab. The currency symbol is picked up from your browser locale or a stored preference, not from anything you enter.
Is 50/30/20 better than zero-based or envelope budgeting?
It is coarser and easier to stick to. Zero-based budgeting assigns every unit of currency to a named category, which is far more precise and far more work; envelope budgeting caps individual categories in cash or in separate accounts. 50/30/20 is best as a first structure or a sanity check on an existing budget — many people start here and move to a category-level budget once the three-bucket split stops telling them anything new.
Where to go next
Read next
- The 50/30/20 budget rule explainedThe full method, where it came from and how to adapt the percentages.
- A complete budget categories listEvery line to sort into needs, wants and savings when you split your statement.
- How much emergency fund do I need?What the savings bucket should be doing before anything else gets funded.
- Zero-based budgeting for beginnersThe category-level method to move to once three buckets stop being enough.
- Budgeting on a freelance or irregular incomeHow to pick the single monthly number this calculator asks you for.
- How to stop living paycheck to paycheckWhat to change first when the needs bucket is running well over 50%.
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