Financial · Live · UK
Mortgage Calculator UK —
monthly payments & SDLT.
Estimate your monthly capital + interest repayment, the total interest you'll pay over the term, and your full upfront cost including Stamp Duty Land Tax (SDLT). Switch between first-time buyer relief and the standard home-mover schedule.
Inputs · GBP
Your UK mortgage
Rates effective 1 April 2025 onwards. England & Northern Ireland only — Scotland uses LBTT, Wales uses LTT.
Monthly repayment
capital + interest · 25-yr term
Stamp Duty Land Tax
First-time buyer relief — band breakdown
| Band | Rate | Slice taxed | SDLT due |
|---|---|---|---|
| Up to £300,000 | 0% | £300,000 | £0 |
| £300,001 to £500,000 | 5% | £50,000 | £2,500 |
| Total SDLT | on £350,000 | £2,500.00 |
Cost summary
What you'll pay, day one and over time
- Property price£350,000
- Deposit (paid upfront)£35,000
- SDLT (paid upfront)£2,500
- Total upfront cost£37,500
- Total repaid over 25 years£566,289
- …of which interest£251,289
Estimates only. Excludes lender arrangement fees, valuation, conveyancing, surveys, and the 5% additional dwellings surcharge for second homes / buy-to-let.
Field guide
How a UK repayment mortgage works.
A standard UK repayment mortgage charges interest each month on your outstanding balance and amortises the loan to zero by the end of the term. Each monthly payment covers all the interest accrued that month, plus a slice of the capital. In the early years interest dominates; in the final years almost every pound goes to capital.
The repayment formula
Lenders compute the constant monthly payment M using the standard amortising formula:
- P: loan principal (property price minus deposit)
- r: monthly interest rate (annual rate ÷ 12)
- n: total number of monthly payments (term years × 12)
Total interest is simply M × n − P. Total upfront cost is your deposit plus SDLT (and, in the real world, lender arrangement fees, valuation, conveyancing, surveys, and the cost of moving — none of which are included here).
Fixed-rate vs. tracker mortgages
Almost every UK mortgage is an initial-rate deal, not a rate fixed for the full term. A fixed-rate deal locks your rate for 2, 3, 5, or occasionally 10 years, then you move to the lender's Standard Variable Rate (SVR) unless you remortgage. A tracker moves directly with the Bank of England base rate plus a fixed margin (e.g. base + 0.75%) for its deal period. Fixes give payment certainty; trackers can be cheaper when rates are falling but carry the risk of rising with the base rate.
Loan-to-value (LTV) and why your deposit size matters twice
Your deposit does two things: it reduces the loan itself, and it moves you into a lower LTV band — the loan expressed as a percentage of the property's value. Lenders price mortgages in bands (commonly 95%, 90%, 85%, 75%, 60% LTV), and each step down usually unlocks a noticeably better rate. Moving from a 90% to an 85% LTV deal (i.e. finding another 5% deposit) is often the single biggest rate improvement available to a typical buyer.
What happens when your fixed or tracker deal ends
When your initial deal expires, you're moved onto the lender's SVR — typically several percentage points higher than any competitive deal. Remortgaging before that happens, either with your existing lender (a "product transfer") or a new one, is how most UK borrowers avoid ever actually paying SVR. Lenders generally let you lock in a new rate 3–6 months before your current deal ends, so re-run this calculator with your new rate as that date approaches.
Help to Buy and other deposit-boosting schemes
England's original Help to Buy equity loan scheme closed to new applicants in 2023, but newer regional and lender-specific low-deposit schemes continue to appear (e.g. Deposit Unlock, various 95% LTV mortgage guarantee products). These typically work by letting you borrow at a higher LTV than a lender would otherwise offer, effectively substituting for deposit you don't have — model the higher LTV rate they carry directly in the calculator above rather than assuming standard-deposit pricing.
Mortgage affordability and disclosure rules follow FCA regulation; SDLT bands are sourced from HMRC (see below). Rates, thresholds, and formulas are checked against FCA and updated when the underlying rules change.
Stamp Duty Land Tax · current rates
Current SDLT bands (England & Northern Ireland).
The temporary higher thresholds introduced in September 2022 expired on 31 March 2025. Since 1 April 2025 the bands below apply to all residential purchases. SDLT is charged marginally: each rate applies only to the slice of the price that falls inside its band. Never to the whole price.
Standard
Home mover · single residence
| Property price band | SDLT rate |
|---|---|
| Up to £125,000 | 0% |
| £125,001 to £250,000 | 2% |
| £250,001 to £925,000 | 5% |
| £925,001 to £1,500,000 | 10% |
| Above £1,500,000 | 12% |
First-time buyer relief
Properties up to £500,000
| Property price band | SDLT rate |
|---|---|
| Up to £300,000 | 0% |
| £300,001 to £500,000 | 5% |
Worked example: Home mover
Buying at £350,000 as a home mover: 0% on the first £125k = £0; 2% on the next £125k = £2,500; 5% on the remaining £100k = £5,000. Total SDLT £7,500.
Worked example: First-time buyer
Same £350,000 as a first-time buyer: 0% on the first £300k = £0; 5% on the next £50k = £2,500. Total SDLT £2,500: relief saves you £5,000 versus the standard schedule.
Disclaimer. This calculator gives illustrative estimates only. SDLT is set by HMRC and may change. A 5% additional dwellings surcharge applies on top of every band for second homes and buy-to-let purchases. Non-resident purchasers pay a further 2% surcharge. Always verify the figure with HMRC's official SDLT calculator and consult your conveyancer before completing.