📋 Budget Calculator
Split your take-home pay into needs, wants and savings, compare it against the 50/30/20 rule, and see at a glance which category is out of line and by how much.
Needs
Wants
Savings and investing
The 50/30/20 rule, and what to do when your numbers do not fit it
The 50/30/20 rule splits take-home pay three ways: half to needs, three tenths to wants, two tenths to savings and debt repayment. It became popular because it is simple enough to remember and generous enough to follow. It is a benchmark, not a law, and the useful part is not hitting the targets — it is seeing by how much you miss them.
Needs ≤ 50% · Wants ≤ 30% · Savings ≥ 20% of take-home pay
Everything is measured against net pay, after tax and deductions, because that is the money that actually arrives. Using gross pay inflates every category and makes the rule meaningless. The take-home pay calculator gives the net figure if you only know your salary.
What counts as a need
A need is something that has consequences if unpaid: rent or mortgage, utilities, basic groceries, transport to work, insurance, minimum debt payments, childcare that makes work possible. A want is everything that would merely be a shame to lose: restaurants, streaming, holidays, the upgraded phone, the gym you intend to use.
Two categories cause most of the arguing. Groceries are a need at the level that feeds you and a want above it — the supermarket shop is a need, the delicatessen is not. Minimum debt payments are a need; anything above the minimum belongs in the savings bucket, because paying down debt faster than required is a form of saving with a guaranteed return equal to the interest rate.
| Category | Needs | Wants | Savings |
|---|---|---|---|
| Rent or mortgage | All | — | — |
| Utilities, phone, internet | All | — | — |
| Groceries | Basic shop | Above it | — |
| Transport | To work | Leisure | — |
| Insurance | All | — | — |
| Debt payments | Minimum | — | Above minimum |
| Eating out, subscriptions | — | All | — |
| Pension, ISA, 401(k) | — | — | All |
Housing is what breaks the rule
In most expensive cities the 50% needs ceiling is not reachable, because rent alone takes 40% or more. Someone on $4,200 a month net paying $1,800 in rent has already used 43% of their income before a single utility bill. Their needs will land near 65%, and no amount of discipline elsewhere will fix it — the shortfall is structural.
When needs run high, the honest response is to decide which of the other two buckets absorbs it. Taking it out of wants preserves the savings rate and makes life austere; taking it out of savings preserves lifestyle and postpones every financial goal. Most people drift into the second without deciding, which is why the savings line is the one worth protecting explicitly.
If needs exceed 60% of take-home pay, the problem is almost always one of the three big fixed costs — housing, car, or debt — rather than daily spending. Cutting coffee cannot close a 10% gap. The house affordability calculator shows what housing cost your income actually supports.
Pay yourself first, or you will not pay yourself
The rule works far better when the savings transfer leaves on payday rather than at the end of the month. Money left to the end of the month reliably is not there, because spending expands to fill the available balance. Automating the 20% out of the current account on the day salary arrives turns saving from a monthly decision into a one-off decision, and the remaining balance becomes the budget without any tracking.
The order within that 20% matters too. The usual sequence is: a small emergency buffer of one month's expenses, then any employer pension match up to the limit, then any debt above roughly 8% interest, then a fuller three to six month emergency fund, then long-term investing. The match comes early because it is an instant return no market can promise — the 401(k) calculator shows what forgoing it costs.
Why 20% and not 10%
Because the savings rate, not the rate of return, is what dominates outcomes for the first fifteen years or so. Saving $700 a month for thirty years at 5% produces about $583,000; saving $350 a month at 7% produces about $426,000. The higher return does not come close to compensating for half the contribution, and you control the contribution.
The savings rate also sets how long you need to work, because it determines both how fast the pot fills and how little you need it to cover. Someone saving 20% lives on 80% and builds a year of spending roughly every four years; someone saving 50% lives on 50% and builds a year of spending every year. See the savings calculator and the investment calculator for the long-run arithmetic.
A worked example
Take-home pay of $5,000 a month. Needs come to $3,350 (67%), wants to $900 (18%) and savings to $750 (15%). Against the rule, needs are $850 over and savings $250 under. The wants figure is already lean, so there is nothing to find there. The $1,450 car payment and insurance inside that needs figure is the real target: moving to a cheaper car frees $400 a month, which lands needs at 59% and savings at 23%. One decision does what a year of small economies could not.
Two neighbours worth knowing: the take-home pay calculator, for the question this one leads into, and the savings calculator, which answers it from the other direction.
Frequently Asked Questions (FAQs)
Is 50/30/20 based on gross or net pay?
Net — take-home pay after tax and deductions. Using gross pay inflates all three categories and makes the benchmark unreachable for most people. If your pension contribution comes out before you see the money, you can count it inside the 20% and budget the rest from what lands.
What if my needs are more than 50%?
Very common, especially in expensive cities. Decide deliberately whether the overflow comes out of wants or out of savings rather than letting it drift out of savings by default. If needs exceed 60%, look at housing, the car, and debt — the big fixed costs — rather than daily spending.
Do minimum debt payments count as a need or a saving?
The minimum payment is a need, because missing it has consequences. Anything you pay above the minimum counts as saving, since clearing debt early earns a guaranteed return equal to the interest rate.
Where does a pension contribution go?
In the savings bucket, including anything your employer matches on your behalf. If the contribution is deducted before your pay arrives, count it in the 20% and treat your net pay as the base for the other two categories.
Is 20% realistic on a low income?
Often not, and treating it as a pass-or-fail test just discourages people. Start with whatever is sustainable — even 5% — and raise it with each pay rise before the money gets absorbed. A rising savings rate beats a high target you abandon in month three.
Should I save or clear debt first?
Build one month of expenses as a buffer, take any employer pension match, then clear debt above roughly 8% before saving more. Below that rate the decision is close enough that either answer is defensible. The debt payoff calculator compares the orderings.
How often should I redo a budget?
Properly once a year, and after any change in income, rent, or household size. Checking in monthly is useful for the first few months while the categories settle, but tracking every transaction forever is a common way to quit. Automating the savings transfer achieves more than tracking does.