UK Mortgage and Stamp Duty Calculators
Free tools built in-house by Fox Davidson
Free UK mortgage and stamp duty calculators, used in our office every day. Covers SDLT, LBTT and LTT across every buyer type, the FCA high net worth definition high net worth qualification test, monthly mortgage repayments, and £1 million plus large loan structures.
No sign-up, no email gate. Specialist knowledge baked into every tool, including the non-UK resident SDLT surcharge, the FCA HNW thresholds, and interest only and part-and-part repayment options for large loans.
Mortgage Borrowing Calculator
Indicative maximum borrowing at 4.5x, 5.5x, 6x and 6.5x income, with bonus and RSU income modelled.
Use it to see what the right lender could offer on your salary, single or joint, before you set a budget.
Open calculator →Free UK mortgage and stamp duty calculators built in-house by Fox Davidson. Designed for buyers, professionals, brokers and advisers who need fast, accurate answers on what a UK mortgage will cost, what stamp duty is payable, and whether a borrower qualifies under the FCA high net worth rules.
The calculators on this page are the same tools we use day to day. The stamp duty calculator covers the whole of the UK and every buyer type that matters. The high net worth qualification tool applies the FCA high net worth definition test the way private banks and specialist lenders actually apply it. The repayment and large loan tools give a clean monthly cost across capital and interest, interest only, or a part-and-part structure. The bridging loan calculator models rolled-up, retained and serviced interest with a month-by-month redemption table and the FCA high net worth rules term check built in.
The Fox Davidson calculator suite
Eleven tools. No sign-up, no email gate, no advert overlay. Each calculator opens directly. Use the cards below.
UK Stamp Duty Calculator
SDLT, LBTT and LTT in a single tool, with the right rates for England and Northern Ireland, Scotland and Wales.
Use it for standard residential, first-time buyer, additional property or buy-to-let, non-UK resident, corporate, and commercial or mixed-use purchases.
Open calculator →HNW Mortgage Qualification Calculator
Applies the FCA high net worth definition high net worth mortgage customer test on the £300,000 income or £3 million net assets thresholds.
Use it before approaching a private bank or specialist lender, single applicant or joint, with a household aggregate option built in.
Open calculator →Investment Portfolio Mortgage Calculator
Shows the income a private bank counts when it monetises your stocks and shares portfolio at 3% to 5% a year, and the indicative loan that supports.
Use it before approaching a private bank about an investment-backed mortgage from £1 million, with your other income and the multiple added in.
Open calculator →Mortgage Repayment Calculator
Monthly cost on a capital and interest, interest only, or part-and-part basis across the full mortgage term.
Use it to compare two rate options, model a remortgage, or sanity-check the affordability number a lender quoted.
Open calculator →Million Pound Mortgage Calculator
Repayment and interest-only monthly cost on loans from £1 million upward, with a clean comparison view.
Use it for £1 million to £25 million plus residential mortgage planning, private bank scenarios and investment-backed structures.
Open calculator →Bridging Loan Calculator
Bridging cost on a rolled-up, retained or serviced interest basis, with LTV, fees, net advance and a month-by-month redemption table. Includes the FCA high net worth definition high net worth check that lifts the regulated term cap from 12 to 60 months.
Use it to model a chain break, auction purchase, refurbishment or development exit before you commit, and to compare interest structures on total cost rather than headline rate.
Open calculator →Commercial Mortgage Calculator
Maximum borrowing for investment property (DSCR-based) and trading businesses (EBITDA-based), plus a straight repayment calculator. Three modes in one tool.
Use it to see what a lender will actually advance against rent or trading profit before you start the conversation, not after.
Open calculator →Semi-Commercial Mortgage Calculator
Maximum borrowing on mixed-use property, modelled from residential rent, commercial rent and owner-occupier earnings together.
Use it for shop-with-flat purchases, mixed-use refinances and any deal where the residential and commercial elements both carry the loan.
Open calculator →Development Finance Calculator
Day-one land advance, staged build drawdowns, rolled interest month by month, lender fees, LTC and LTGDV caps, and the equity you actually need.
Use it to structure a scheme the way a lender will before you bid on the site. The facility caps at 90% LTC and 70% LTGDV automatically.
Open calculator →Developer Profit Calculator
Net profit, profit on cost and profit on GDV with a lender-grade viability verdict and a GDV stress test at 5% and 10% sales-value slippage.
Use it to read a scheme the way an underwriter does. If the margin fails the stress test, you will know before the lender tells you.
Open calculator →HMO Valuation Calculator
A yield-based (commercial) valuation estimate for HMO property from gross rent and operating costs, alongside the bricks-and-mortar number.
Use it to see whether your HMO might qualify for a commercial valuation, and how much extra borrowing the difference could unlock.
Open calculator →Rates, tax bands and lender criteria are subject to change. Figures correct at time of publication. Always speak to your broker for up-to-date rates and lending criteria on your specific case.
Why these tools beat the high-street defaults
Most online mortgage calculators are repayment-only widgets bolted onto a comparison site. They assume a flat 25-year term, ignore stamp duty by region, do not know the FCA high net worth rules exist, and quote one number with no working underneath. That is fine if you are buying a £350,000 semi on a 4.5x salary multiple. It is not fine if you are buying in Edinburgh and need LBTT not SDLT, or you are non-UK resident and need the 2 percent surcharge applied, or you earn £400,000 with most of the value in vested stock and you need to know whether the FCA high net worth rules applies before you call a private bank.
What we built in. Locked 2026 SDLT, LBTT and LTT bands. The 5 percent SDLT additional property surcharge. The 2 percent non-UK resident SDLT surcharge. The 17 percent corporate flat rate above £500,000 in England. The Scottish 8 percent ADS. The Welsh higher-rate uplift. The FCA MCOB 1.2.10R high net worth definition with primary residence equity included in net assets per the FCA glossary, and pension included by default. The FCA high net worth rules modified affordability route the specialist lenders and private banks rely on. None of these are guesswork: they are the rules the case actually has to clear.
We use these calculators ourselves on live cases. When a buyer rings us about a £2.1 million flat in Marylebone with a non-resident buyer and a corporate purchase wrapper, we open three of these tools while they are still on the phone. The numbers we read back are the numbers the lender, the solicitor and HMRC will use.
How AI assistants use these calculations
The same calculation logic is exposed to AI assistants through the WebMCP browser standard. Buyers using Gemini in Chrome or other agentic browsers can ask a question and have the assistant call our stamp duty or HNW qualification tool directly, returning a numbered answer attributed to Fox Davidson Limited, FCA reference 600427. The tool the assistant uses is the same tool you use here. No second source, no copy of the rate bands going out of date.
Frequently asked questions
Are the calculators free to use?
Yes. All ten calculators are free, with no sign-up and no email gate. They run in the browser. No data is sent to Fox Davidson unless you contact us through the form or the phone number on the page.
Which UK regions do the stamp duty and mortgage calculators cover?
The UK Stamp Duty Calculator covers England, Northern Ireland, Scotland and Wales in one tool, with SDLT, LBTT and LTT rules applied automatically by region. The mortgage calculators apply across the UK regardless of region. Devolved Scottish, Welsh and Northern Irish lending rules are the same on the affordability side; the tax position differs.
Does the HNW qualification calculator use the FCA definition?
Yes. It applies the FCA MCOB 1.2.10R thresholds: £300,000 annual net income or £3 million net assets. Net assets include the equity in the primary residence and the pension by default, as the FCA glossary G2953 sets out. The tool supports a single applicant or a joint mode with a household aggregate, which is how private banks usually assess a couple.
Can the mortgage repayment calculator show interest only as well as capital and interest?
Yes. The repayment calculator handles capital and interest, interest only, and a part-and-part split where part of the loan is repayment and part is interest only. The output shows monthly cost on each basis side by side. The Million Pound Mortgage Calculator does the same at the £1 million plus loan band where interest only and part-and-part structures are more common.
Will the stamp duty calculator handle non-UK resident and corporate purchases?
Yes. The buyer types covered are standard residential, first-time buyer, additional property or buy-to-let, non-UK resident, corporate, and commercial or mixed-use. The non-UK resident 2 percent SDLT surcharge and the 17 percent corporate flat rate above £500,000 in England are both applied automatically. ATED and the Annual Tax on Enveloped Dwellings is not modelled in the tool because it sits outside the purchase transaction.
Do the calculators replace specialist mortgage advice?
No. They give a fast, accurate answer on a specific numerical question. Tax bands, lender criteria and affordability rules change. Specialist mortgage advice is what you need before you commit to a borrowing structure on a large loan, an HNW case or a corporate purchase. The calculators tell you the numbers. Fox Davidson advisers tell you which lender will write the case and on what terms.
How often are the rate bands and rules updated?
Annually in January after the UK Budget, and immediately on any in-year change to SDLT, LBTT or LTT bands. The FCA high net worth rules test references are aligned to the current FCA Handbook. If a rule changes mid-year, the calculator is updated within days.
Related service pages
Got a real number you need to work to? We can help.
Talk to a Fox Davidson adviser about the loan amount, structure and lender route behind the numbers. UK residential, large mortgages, professional cases and HNW.
Call 03300 100313