Finance Calculators
Work out a mortgage payment, what a pay rise is really worth, how long savings will last, or what a credit card is costing you. Every calculator shows its formula and the figures behind the answer.
Which calculator do I need?
Several of these overlap. This is the quickest way to the right one.
- What will my monthly mortgage payment be?
- Mortgage Calculator
- How much sooner would overpaying clear it?
- Mortgage Payoff
- What rate band does my deposit put me in?
- LTV Calculator
- How much of each payment is interest?
- Amortization Schedule
- What will I actually take home?
- Take-Home Pay
- What is my pay rise worth after tax?
- Pay Rise Calculator
- How long will this credit card take to clear?
- Credit Card Payoff
- What will my savings grow to?
- Savings Calculator
- How long will my savings last if I draw on them?
- How Long Will My Money Last
- Was that investment actually any good?
- ROI Calculator
Finance guides
Longer explanations of the maths behind the tools, and the decisions they inform.
Understanding Your Finances
Loans and repayments
Any loan — mortgage, car, personal — works the same way mathematically: you borrow a principal, pay interest on the outstanding balance, and repay in equal instalments. The key variables are principal, annual interest rate, and term. Changing any one of them shifts the monthly payment and total interest paid.
Compound interest fundamentals
Compound interest earns returns on both the original principal and the accumulated interest. The more frequently interest compounds — daily vs monthly vs annually — the faster your balance grows. This works for you in savings accounts and against you in credit card debt where the balance compounds monthly.
Investment return basics
Return on investment (ROI) measures profit relative to cost. Annualised ROI lets you compare investments held for different periods on a level footing. Compound annual growth rate (CAGR) shows the year-on-year growth rate that would produce the same end result as the actual investment.
Mortgage key terms
Loan-to-value (LTV) is your mortgage as a percentage of the property value — lower LTV means better rates. Amortization is the process of paying off the loan through regular payments. An amortization schedule shows exactly how much of each payment goes to interest versus principal over the full loan term.
Finance calculator questions
- Which mortgage calculator should I use?
- Use the Mortgage Calculator to find the monthly payment on a new mortgage. Use the Mortgage Payoff Calculator if you already have one and want to know what overpaying would save. Use the Amortization Schedule if you want to see how each individual payment splits between interest and capital.
- Are these calculators UK-specific?
- The tax and salary tools are: Take-Home Pay and Pay Rise use UK income tax bands, National Insurance and student loan plans, and state the tax year they apply to. The mortgage, savings and investment tools are arithmetic and work anywhere, with a currency selector. The Auto Loan calculator is the one deliberate exception, modelling US sales tax and fees.
- Do I need to sign up or enter any personal details?
- No. Every calculation runs in your browser and nothing you type is sent anywhere. There is no account, and no figure you enter leaves your device.
- How accurate are the results?
- Each tool publishes the formula it uses, the assumptions it makes and the sources behind any rates, along with the date those sources were last reviewed. Results are estimates for planning, not a quote or financial advice — a lender or adviser will account for fees and circumstances a calculator cannot see.