About Kleinfeld Mortgage Calculators

Kleinfeld Mortgage Calculators is a free, independent website providing 24 UK-focused calculators covering mortgages, property costs and personal finance. Every tool is built specifically around UK rules, rates and conventions — not adapted from a US or generic template — and is kept updated for the current 2026/27 tax year.

What We Offer

Our calculators are organised into three groups:

• Mortgage — including our core Mortgage Calculator, Affordability and Borrowing calculators, Compare Two Mortgages, Compare Fixed Rate Mortgages, Mortgage Rate, Extend Mortgage Term, Overpayment, Offset Mortgage, Mortgage Deposit Savings, Interest-Only vs Repayment, Remortgage, Buy to Let, Bridging Loans, Equity Release, and Mortgage Protection Insurance.
• Property — Stamp Duty (SDLT), Property Value, and Rental Yield calculators.
• Money & Insurance — Income Tax, Salary (take-home pay), Lifetime ISA, Life Insurance, and a live Currency Converter.

You can browse the full list of calculators on our Sitemap.

How We Work

Every calculator runs entirely in your web browser — there is no sign-up, no account, and no need to hand over personal or financial details to get a result. Nothing you type into a calculator is sent to, or stored on, our servers. See our How It Works page for more detail on the formulas and rates behind each calculator, and our Privacy Policy for how we handle any data we do collect (for example, if you contact us directly).

Our Approach

We believe understanding the real cost of a mortgage, a property purchase, or a financial decision should not require jargon, sign-up forms, or sales pressure. Our calculators are designed to be clear, fast, and genuinely useful for exploring “what if” scenarios before you speak to a professional — whether that is comparing two mortgage deals, working out how much deposit you need, or estimating your take-home pay.

Kept Up to Date

UK tax bands, Stamp Duty thresholds, National Insurance rates, ISA allowances and lending conventions all change over time — including at Budget events. We review and update the rates behind our calculators to reflect the current tax year, so the figures you see stay relevant.

Not Financial Advisers

We are not a firm of mortgage brokers or financial advisers, and we are not authorised or regulated by the Financial Conduct Authority (FCA). Nothing on this Site constitutes regulated financial, mortgage, tax or legal advice — our calculators are designed to help you understand your options before you speak to a qualified, regulated professional or lender. See our Disclaimer for more information.

Questions or Feedback?

If you spot an error, have a suggestion for a new calculator, or just want to get in touch, please visit our Contact page — or take a look at our FAQ for answers to common questions.