The free, official and reliable UK money calculators worth bookmarking: take-home pay, State Pension forecast, benefits, budgeting, mortgages and Stamp Duty, savings, debt, student loans and childcare, with tips for using them well.
Online calculators can answer money questions in minutes, but quality varies. The best ones are free, run by government or independent bodies, and kept up to date with tax rules. These are the ones worth bookmarking, with notes on what each can and can't tell you.
Pay and tax
- HMRC's estimate of your Income Tax: GOV.UK has an Income Tax estimator for the current year. Your personal tax account also shows your tax code and an estimate of what you'll pay.
- Take-home pay: independent salary calculators show tax, National Insurance, pension and student loan deductions. Check they're set to the right tax year and to Scotland if you live there, as Scottish Income Tax rates differ.
Use these to check your payslip, compare job offers, or see the effect of a pay rise or extra pension contributions.
Pensions
- Check your State Pension forecast on GOV.UK. It shows how much you could get, when, and whether you have gaps in your National Insurance record. You may be able to fill gaps with voluntary contributions; check whether it's worth it first.
- Pension calculators: MoneyHelper has a free pension calculator that estimates your retirement income from your current savings and contributions.
- Pensions dashboards are being rolled out to let you see all your pensions in one place.
Benefits
GOV.UK links to free, anonymous benefits calculators run by independent organisations. They estimate what you might be entitled to, including Universal Credit, Pension Credit, Council Tax Reduction and help for carers. Millions of pounds in entitlements go unclaimed each year, so it's worth checking after any change in circumstances.
Budgeting
MoneyHelper's budget planner walks you through income and outgoings, including irregular bills, and shows where your money goes. It's free and doesn't need an account.
Housing
- Mortgage calculators: estimate monthly payments for different rates and terms. MoneyHelper has an independent one.
- Affordability calculators: give a rough idea of how much lenders might offer. Treat them as a ceiling, not a target.
- Stamp Duty Land Tax calculator: HMRC's official calculator works out SDLT for property in England and Northern Ireland. Wales (Land Transaction Tax) and Scotland (LBTT) have their own.
- Rent vs buy comparisons: helpful, but sensitive to assumptions about house prices and interest rates.
Savings and investing
- Savings calculators show how regular saving and interest grow over time. Compound interest makes a big difference over long periods.
- Inflation calculators: the Bank of England's shows how prices have changed over time.
- Investment calculators: remember that past returns don't guarantee future ones, and fees reduce returns.
Debt
- Loan and credit card repayment calculators show how long it takes to clear a balance and the interest you'll pay. Paying only the minimum on a credit card can take years.
- Debt charities such as StepChange have tools to help you work out what you can afford to repay.
Student loans
GOV.UK explains repayment thresholds for each plan. Calculators can estimate repayments, but for many graduates, especially on newer plans, the loan is written off before it's fully repaid, so the monthly deduction matters more than the balance.
Childcare
The government's childcare calculator on GOV.UK shows which help you could get, such as Tax-Free Childcare and funded hours, and how to apply.
Using calculators well
- Check which tax year and which UK nation the calculator assumes.
- Use accurate inputs: payslips, statements and bills.
- Try a cautious scenario as well as a likely one.
- Remember calculators give estimates, not advice. For big decisions, speak to a regulated adviser or a free guidance service such as MoneyHelper or Pension Wise.
- Be wary of calculators on sites that sell products, which may be designed to steer you.
Frequently asked questions
Are online calculators accurate?
Good ones are accurate for standard situations, but can't reflect every detail. Use official sources where possible.
Do benefits calculators store my data?
The GOV.UK-listed calculators are anonymous, but check each one's privacy notice.
Sources and further reading
- GOV.UK: Check your State Pension forecast
- GOV.UK: Benefits calculators
- GOV.UK: Calculate Stamp Duty Land Tax
- Bank of England: Inflation calculator
- GOV.UK: Childcare calculator
- GOV.UK: Repaying your student loan
Facts checked on 20 October 2026. Spotted an error? Tell us and we will correct it.