Hundred SummersHousehold budget calculator: your monthly surplus, and where it goes next
What comes in against what goes out each month, the surplus or shortfall, how far your cash would stretch, and the order a surplus usually goes. Your figures never leave your browser.
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Worked example
Computed when this page was built by the same engine that runs the calculator above, so the figures below and the live tool can never disagree. Change any input above to see your own.
| Inputs | |
|---|---|
| Take-home pay a month | £4,000 |
| Essentials a month | £2,650 |
| Everything else a month | £740 |
| Cash savings / expensive debt | £5,000 / £2,500 |
| Results | |
|---|---|
| Left over each month | £610 |
| As a share of income | 15% |
| Months of essentials in cash | 1.9 |
| Next step | Expensive debt cleared: about 5 months from now |
The next question
What do I own, and how much of it can I reach? →Net worth calculator
Or answer it with everything else: the full Hundred Summers plan connects your pay, pensions, savings, property, tax and spending year by year, and stress-tests them across 500 simulated market histories.
Read the guide
- Premium Bonds, cash and tax: where the money you might need should sit →The personal savings allowance and why higher-rate savers cross it at ordinary balances, the after-tax comparison that decides Premium Bonds against a savings account, cash ISAs, and what inflation does to money that sits still.
Essentials first
The budget splits spending in two. Essentials are what you would still pay if your income stopped: housing, council tax, energy, food, transport, phone, insurance, childcare and minimum debt repayments. Everything else is where a shortfall is usually closed. The split matters twice over: essentials set the size of an emergency fund, and the surplus after both is the money every other decision draws on.
Where a surplus goes
Most money guides set out the same sequence: a month's buffer, then expensive debt, then a full emergency fund of three to six months, then any employer pension match, then long-term saving. Each step has a calculator: the emergency fund, debt payoff, salary sacrifice and ISA vs pension calculators. The net worth calculator shows the balance sheet the surplus builds.
Sources
- MoneyHelper, Budget planner.
- MoneyHelper, Emergency savings: how much is enough?