50 finance tools, grouped by the decision you are making
Money questions rarely arrive one at a time. The sections below follow the order most household finances actually move in: know what you spend, build a buffer, deal with debt, understand your pay, then plan for a home and retirement. Jump straight to the area you need.
Every calculator in this section now carries a full explanation: what it works out, how the method works, a worked example you can reproduce, the mistakes people make, and answers to the questions that come up most. Where a tool relies on a tax rate, threshold or allowance, that figure is an editable field rather than fixed in the code.
Start here
If you are not sure where to begin, these tools answer the questions readers ask most often in this section.
Budgeting and household spending 9 tools
Build a picture of what actually goes out each month, plan for irregular costs and check whether the household budget is holding together.
Saving and investing 8 tools
Project what regular saving or a lump sum could become, keep track of allowances and understand what inflation does to the result.
Borrowing and debt repayment 7 tools
Compare the true cost of credit, test repayment strategies and see how long a balance will realistically take to clear.
Pay, tax and employment 9 tools
Convert between pay periods, estimate deductions and plan around a change in employment.
Property and moving home 5 tools
Test what is affordable, understand the cost of buying and see what overpaying a mortgage actually achieves.
Pensions and retirement 4 tools
Check contribution levels, spot a shortfall early and translate a pension pot into an indicative income.
Spending decisions and value 7 tools
Settle the small recurring questions: is this worth buying, is it worth repairing, and is the bigger pack actually cheaper?
What these tools can and cannot tell you
Every calculator here is an estimate built from the figures you enter. That makes them useful for comparing options and testing assumptions, and unsuitable as a final answer on anything binding.
Where the results are reliable
- Arithmetic that follows directly from your inputs — totals, unit prices, pay conversions and elapsed time — is exact.
- Comparisons between two options entered on the same basis are dependable, because any shared assumption cancels out.
- Direction of travel is dependable: if a tool shows that overpaying shortens a mortgage term, it will.
Where the results are only indicative
- Anything involving a future rate — investment growth, inflation, interest — is a projection, not a forecast.
- Tax and deduction estimates simplify a system full of edge cases: student loan plan types, tax code adjustments, benefits and marriage allowance are not modelled.
- Lender affordability decisions use credit history and stress-testing that no public calculator can reproduce.
Not financial advice. These calculators are for information and planning. They do not take account of your personal circumstances and are not regulated financial advice. Confirm current rates and thresholds on GOV.UK, and consider free guidance from MoneyHelper or Citizens Advice before acting on a result.
The sources behind the tax bands, allowances and formulas used in this section are listed on the references page, and the way each tool is written and checked is set out in my editorial policy.
Common questions
Are these calculators specific to the UK?
Most are. Pay, tax, ISA, stamp duty, student loan and State Pension tools are built around UK rules and use UK terminology. Where a threshold, rate or allowance is involved it is shown as an editable field rather than fixed in the code, so the tool still works after a Budget changes the figures — and so readers outside the UK can substitute their own values.
Do the tax and allowance figures update automatically?
No. Rates, thresholds and allowances are entered by you, with a sensible default supplied. This is deliberate: an automatically updated figure that silently goes stale is more dangerous than one you had to confirm yourself. Always check the current figure against GOV.UK before relying on a result.
Is any of this financial advice?
No. These are calculators, not recommendations. They show the arithmetic behind a decision so you can see how the numbers behave. They cannot account for your full circumstances, and they do not know about your tax position, your debts elsewhere or your plans. For a decision that matters, speak to a qualified adviser, and use free services such as MoneyHelper or Citizens Advice if cost is a barrier.
Is anything I type sent to a server or saved?
No. Every calculator on this page runs entirely in your browser using JavaScript. Salary figures, debt balances and account values are never transmitted to me and are not stored as calculator records. Closing the tab discards them.
Why do two calculators give slightly different answers?
Usually because they make different assumptions. A mortgage overpayment tool that compounds monthly will not match one that compounds annually, and a payslip estimate that ignores a workplace pension will differ from one that includes it. Each page states its method and assumptions; read those before comparing outputs.
Which tool should I use first?
If money feels tight, start with the Household Budget Planner and then the Emergency Fund Calculator. If you are carrying debt, the Credit Card Repayment Calculator usually produces the most useful shock. If things are stable and you are planning ahead, start with the Pension Gap Checker.
Related subjects
Questions rarely sit inside a single subject. These sections cover the calculations most often needed alongside money and budgeting.