Free Online Financial Calculators for UK Businesses
FinToolbox is a free set of financial calculators built for UK business owners, sole traders, landlords, and individuals who need quick, reliable figures without the jargon. There are no sign-ups, no paywalls, and no unnecessary complexity — just straightforward tools that work.
Whether you're adding VAT to an invoice, estimating your income tax before self-assessment, or working out the stamp duty on a property purchase, every calculator uses the latest HMRC rates and thresholds. All results are instant and shown clearly in pounds sterling.
Tools are organised into five categories. VAT calculators cover standard and reduced rates, reverse VAT, the Flat Rate Scheme, import VAT, and the £90,000 registration threshold. Tax calculators cover income tax, National Insurance (Class 1 and 4), capital gains, dividend tax, inheritance tax, and self-assessment estimates for 2026/27. Business calculators include corporation tax with marginal relief, payroll costs, profit margins, break-even analysis, cash flow forecasting, and loan repayments. Property calculators handle stamp duty (including first-time buyer relief), mortgage repayments, overpayment savings, buy-to-let yield, and remortgage comparisons. Marketing calculators cover ROI, ROAS, customer acquisition cost, lifetime value, and conversion rate modelling.
All figures are estimates based on published HMRC guidance and standard financial formulas. FinToolbox does not provide financial or tax advice — for complex situations, consult a qualified accountant or adviser.
Popular Calculators
- VAT Calculator Add or remove UK VAT at 20%, 5%, or 0% in seconds.
- Income Tax Calculator Calculate your UK income tax for 2026/27 across all rate bands.
- Stamp Duty Calculator Calculate SDLT for residential purchases, including first-time buyer relief and additional dwelling surcharge.
- Mortgage Repayment Calculator Calculate your monthly mortgage payment and total cost over the term.
- National Insurance Calculator Calculate Class 1 (employee) or Class 4 (self-employed) NI contributions.
- Corporation Tax Calculator Calculate UK corporation tax at 19% or 25% with marginal relief for FY2025.
- Compound Interest Calculator Calculate the final value, total interest earned, and effective annual rate for any savings or investment using compound interest.
- Payroll Calculator Calculate employee take-home pay and total employer cost including NI.
Add or remove VAT, check your registration threshold, and calculate Flat Rate Scheme savings — all using current HMRC rates.
- VAT Calculator Add or remove UK VAT at 20%, 5%, or 0% in seconds.
- Reverse VAT Calculator Extract the net amount and VAT from any gross (VAT-inclusive) figure.
- VAT Flat Rate Scheme Calculator Calculate your VAT liability and potential saving under the HMRC Flat Rate Scheme.
- VAT Registration Threshold Calculator Check whether your turnover is approaching the £90,000 VAT registration threshold.
- Import VAT Calculator Estimate the import VAT and customs duty payable on goods imported into the UK.
Estimate income tax, National Insurance, capital gains, and dividend tax for the 2026/27 UK tax year.
- Income Tax Calculator Calculate your UK income tax for 2026/27 across all rate bands.
- National Insurance Calculator Calculate Class 1 (employee) or Class 4 (self-employed) NI contributions.
- Capital Gains Tax Calculator Work out CGT on residential property or other assets for 2026/27.
- Dividend Tax Calculator Calculate the tax due on UK dividends above the £500 annual allowance.
- Self Assessment Tax Bill Calculator Estimate your total self-assessment bill including income tax, NI, and CGT.
Plan and run your business with tools for corporation tax, payroll, cash flow, loan repayments, and profit margins.
- Corporation Tax Calculator Calculate UK corporation tax at 19% or 25% with marginal relief for FY2025.
- Payroll Calculator Calculate employee take-home pay and total employer cost including NI.
- Profit Margin Calculator Calculate gross, operating, and net profit margins for your business.
- Business Loan Calculator Calculate monthly repayments and total interest on a business loan.
- Cash Flow Forecast Calculator Build a simple 12-month cash flow projection for your business.
Calculate stamp duty, mortgage repayments, rental yield, and potential savings from overpaying or remortgaging.
- Stamp Duty Calculator Calculate SDLT for residential purchases, including first-time buyer relief and additional dwelling surcharge.
- Mortgage Repayment Calculator Calculate your monthly mortgage payment and total cost over the term.
- Mortgage Overpayment Calculator See how much interest you save and how many years you cut by overpaying your mortgage.
- Buy-to-Let Yield Calculator Calculate gross and net rental yield on a buy-to-let property investment.
- Remortgage Savings Calculator Compare your current mortgage with a new deal and find your break-even point on fees.
Measure campaign efficiency with calculators for ROI, ROAS, customer acquisition cost, lifetime value, conversion rates, and churn.
- ROI Calculator Calculate return on investment and net profit for any business spend.
- ROAS Calculator Calculate return on ad spend to measure the effectiveness of your advertising.
- Customer Acquisition Cost Calculator Calculate CAC by channel to understand the true cost of acquiring a customer.
- Customer Lifetime Value Calculator Estimate gross and net LTV based on order value, purchase frequency, and lifespan.
- Conversion Rate Calculator Calculate your conversion rate and model the revenue impact of a rate improvement.
Build your financial safety net, pay off debt strategically, and harness the power of compound interest with our personal finance tools.
- Emergency Fund Planner Calculate your ideal emergency fund target (3–6 months of expenses) and see how long it takes to reach it.
- Debt Snowball vs Avalanche Calculator Compare the debt snowball and avalanche repayment strategies to see which saves the most interest and pays off debt fastest.
- Compound Interest Calculator (Savings) Calculate how a lump-sum savings deposit grows over time with compound interest and see your effective annual rate.
Simulate portfolio growth, assess risk-adjusted returns with the Sharpe ratio, and plan your long-term investment strategy.
Calculate statutory redundancy pay and understand your employment entitlements using the latest HMRC rates and rules.