Finance & Tax
High-accuracy loan, tax and savings calculators
About finance & tax
A financial calculator is only useful if you can trust the number it gives you. Most online calculators hide their assumptions behind a single result, so you have no way of knowing whether the payment they show includes property tax, whether the APR accounts for an origination fee, or whether the amortization schedule actually reconciles to zero in the final month.
Every ToolNest finance calculator is built on the published formula from the regulator or agency that governs it — the CFPB and Regulation Z for consumer credit, the Federal Reserve for APR disclosure, Freddie Mac Form 91 for remaining mortgage balance, the SEC Investor.gov formula for compound growth, HMRC VAT Notice 700 for UK tax, and the EU VAT Directive for cross-border rates. Each page shows the formula, walks through a worked example, and exports the full amortization schedule so you can check the arithmetic yourself.
Who these tools are for
Homebuyers and homeowners
Model a mortgage payment with taxes, insurance, PMI and HOA included, test how an extra monthly payment shortens the term, compare a refinance against your current loan to find the exact break-even month, and work out how much house your income actually supports under the 28/36 debt-to-income rule.
Borrowers paying down debt
See how long a credit card really takes to clear on minimum payments, compare a fixed payment against a target payoff date, weigh debt avalanche against debt snowball, and check whether a 0% balance transfer is worth the fee once the promotional period ends.
Savers, freelancers and cross-border buyers
Project compound growth with monthly contributions and inflation adjustment, and add or remove sales tax and VAT using built-in rates for all 50 US states, the UK and all 27 EU member states — including the reverse-VAT calculation that trips up most people.
All finance & tax
Every calculator below is live and fully working. Each one runs entirely in your browser, shows its official formula, and exports the full schedule so you can check the arithmetic yourself.
Mortgage Payment Calculator
LiveCalculate monthly mortgage payments with taxes, insurance, PMI, HOA and extra payments, plus a full amortization schedule.
Open calculatorAuto Loan Calculator
LiveEstimate car loan payments including trade-in value, sales tax, dealer fees and term comparisons.
Open calculatorPersonal Loan Calculator
LiveWork out personal loan repayments, origination fees and the true APR you actually pay.
Open calculatorCompound Interest Calculator
LiveProject savings and investment growth with monthly contributions, any compounding frequency and inflation adjustment.
Open calculatorSales Tax & VAT Calculator
LiveAdd or remove sales tax and VAT using built-in rates for all 50 US states, the UK and all 27 EU countries.
Open calculatorMortgage Refinance Calculator
LiveCompare your current mortgage with a refinance, find the exact break-even month and lifetime interest savings.
Open calculatorHELOC Calculator
LiveCalculate your home equity line of credit limit from LTV, then model draw-period and repayment-period payments.
Open calculatorMortgage Affordability Calculator
LiveFind how much house you can afford using the official 28/36 DTI rule, with FHA and VA presets.
Open calculatorCredit Card Payoff Calculator
LiveSee how long minimum payments really take, then compare fixed payments and avalanche vs snowball strategies.
Open calculatorCredit Card Balance Transfer Calculator
LiveCompare a 0% balance transfer against your current card, including the transfer fee and post-promo APR.
Open calculator
Finance tools — common questions
- Which official formulas do these calculators use?
- Mortgage and loan payments use the Regulation Z Appendix J amortising payment formula. Remaining balance uses Freddie Mac Form 91. True APR uses the Regulation Z actuarial method solved by Newton-Raphson iteration. Compound growth uses the SEC Investor.gov formula, and APY uses the Truth in Savings Act definition. Sales tax and VAT follow HMRC VAT Notice 700 and the EU VAT Directive.
- Are the results accurate enough to use for real decisions?
- The maths is exact to the cent and every schedule reconciles to a zero balance in the final payment. However, lenders apply their own rounding, day-count conventions and fee rules, so treat the output as a precise model rather than a binding quote. Always confirm the final figure with your lender or tax authority.
- Do the calculators support USD, GBP and EUR?
- Yes. Every calculator has a currency switcher at the top that converts the display between US dollars, British pounds and euros. The underlying maths is currency-agnostic, so switching currency never changes the result — only how it is formatted.
- Can I save or share a calculation?
- Yes. The Share button copies a link that encodes every input in the URL, so you can bookmark a scenario or send it to a partner, broker or accountant. The CSV button downloads the full schedule for use in Excel, Numbers or Google Sheets.
- Is my financial data sent to a server?
- No. Every calculation runs entirely in your browser. Your loan amounts, income and balances are never transmitted, logged or stored. The only network requests are for the page itself and, where you have consented, advertising.
- Are these calculators financial advice?
- No. They are educational modelling tools. They do not account for your full financial circumstances, credit history, local taxes or lender-specific criteria. Speak to a qualified mortgage adviser, accountant or debt counsellor before making a financial commitment.