How is my monthly mortgage payment calculated?

Your monthly payment is calculated using the annuity formula: P × r(1+r)^n / ((1+r)^n - 1), where P is the loan amount, r is the monthly interest rate, and n is the number of monthly payments. Early payments are mostly interest; later ones mostly capital.

What is LTV and why does it matter?

Loan-to-Value (LTV) is your mortgage as a percentage of the property value. A lower LTV means less risk for lenders, so they offer lower interest rates. Key thresholds are 95%, 90%, 85%, 80%, and 75% — dropping below each usually unlocks better rates.

What is the difference between repayment and interest-only?

With a repayment mortgage each payment reduces both the capital and the interest, so the mortgage is fully paid at the end of the term. With interest-only you only pay the interest each month — the capital remains and must be repaid in full at the end.

What is equity in a property?

Equity is the portion of your property that you own outright — the difference between the current market value and the outstanding mortgage balance. For example, if your home is worth £300,000 and your mortgage balance is £200,000, you have £100,000 of equity (33%). Equity grows as you repay your mortgage and as your property value increases. It can be accessed through remortgaging or selling.

Should I overpay my mortgage?

Overpaying reduces your outstanding balance faster, cutting the total interest you pay and shortening your term. On a £200,000 mortgage at 4.5% over 25 years, overpaying £200/month saves around £28,000 in interest and pays off the mortgage 6 years early. Before overpaying, check your lender's annual overpayment limit — most allow 10% of the balance per year without an early repayment charge.

What happens when my fixed rate ends?

When your fixed rate deal ends you are automatically moved onto your lender's Standard Variable Rate (SVR), which is typically much higher — currently averaging around 7%. You should start looking for a new deal up to six months before your fix ends. Remortgaging to a new fix or switching products with your existing lender (a product transfer) are the two main options.

What are current UK mortgage rates?

As of March 2026, average 2-year fixed rates sit around 5.0% and 5-year fixes around 5.1%. The best deals for those with 40%+ equity are closer to 3.8–4.1%. The Bank of England base rate is currently 3.75%. Rates have been falling gradually and further cuts are expected through 2026 — though global factors including Middle East tensions have added near-term uncertainty.

🇬🇧 UK Financial Tools · 2026/27

UK Mortgage Calculator
monthly payments & total cost

Calculate repayments, compare rates and see the true cost of your mortgage — always up to date.

✓ Updated for 2026/27 tax year ✓ Uses official HMRC tax bands ✓ No personal data stored ✓ Free — always

Mortgage Calculator

Estimate your monthly repayments, total interest, and full cost of ownership.

Property Price

Deposit

Interest Rate (Annual %)

5.25%

Mortgage Term (Years)

25y

Mortgage Type i

Rate Type i

📌 Fixed rate: your repayment is predictable and immune to rate rises during the fixed period.

💰 Buying Costs (Optional)

Stamp Duty i

Auto-estimated below — or enter manually to override

Survey Costs

Legal Fees

Broker Fee

Product Fee

Buyer type (for SDLT estimate)

Add product fee to loan amount? (increases interest paid)

📊 Affordability Check

Annual Household Income

Monthly Take-home Pay

Repayment Summary

Live

Monthly Payment

£—

Loan Amount—

Effective Balance (after offset)—

Total Repaid—

Total Interest—

Interest saved by offset—

Interest : Capital—

CapitalInterest

🏡

Find the best mortgage rates

Compare 2-year and 5-year fixed deals from across the market. (affiliate link)

Compare rates →

🔗 Related Calculators

💡 Helpful tip

A 10% deposit (90% LTV) gets you on the ladder, but saving to 15–20% (80–85% LTV) unlocks significantly cheaper rates — often saving £100–200/month.

📈 Rate Over Time

Most people don't stay on one rate for 25+ years. Model your initial deal, then what happens when you revert to SVR.

Initial Fixed Period (Years) i

Initial Fixed Rate (%)

4.5%

Revert-to SVR Rate (%) i

7.99%

🔮 Rate Rise Scenarios

Stress test: add to SVR (%)

💡 Tip: Uses the loan & term from the Basic tab. Set those first for accurate results.

Rate Scenario

Live

Fixed Period

£—

per month

After Revert

£—

per month (SVR)

Monthly jump at revert—

Interest during fixed period—

Interest after revert (remaining term)—

Total interest (full term)—

Balance remaining at revert—

—

⚡ Remortgage tip: Remortgaging before your fixed period ends (typically 3–6 months before) can save thousands compared to rolling onto SVR.

💸 Overpayment Calculator

See how extra payments slash years off your mortgage and save thousands in interest.

Monthly Overpayment i

Annual Lump Sum Overpayment

One-off Overpayment (now)

ℹ️ How it works: Overpayments reduce your outstanding capital. This means less interest each month, which compounds to significant savings over the term.

⚠️ ERC warning: Many fixed-rate deals limit overpayments to 10% of the balance per year. Exceeding this triggers an Early Repayment Charge (typically 1–5% of the overpaid amount). Check your mortgage terms.

Overpayment Impact

Live

Without overpaying

—

to pay off

With overpayments

—

to pay off

Years shaved off—

Interest without overpaying—

Interest with overpayments—

Total interest saved—

New payoff date—

10% ERC limit (annual)—

Enter overpayment amounts to see the impact.

📈 Amortisation Chart

How your monthly payment splits between capital repayment and interest over time. Hover for exact figures.

Capital repaid Interest paid

🍰 Total Cost Breakdown

What proportion of your total repayment is pure interest vs capital.

📉 Balance Over Time

Shows how slowly balances reduce early on — the mortgage "hockey stick".

⚡ Notice how most capital is repaid in the final years — this is why the first years feel slow and why overpaying early has a powerful compounding effect.

📅 Mortgage Timeline

Visualise your mortgage journey — when rates change, when your LTV crosses key thresholds, and when you're free.

Fixed deal settings

Initial fixed period (years)

Fixed rate (%)

4.5%

SVR after fixed period (%)

7.99%

💡 Uses property price, deposit, and term from the Basic tab. Set those first.

Key Milestones

Visual Timeline

Scenario A

Property price

Deposit

Interest rate (%)

4.5%

Term (years)

25y

Mortgage type

Scenario B

Property price

Deposit

Interest rate (%)

3.89%

Term (years)

25y

Mortgage type

Side-by-side Comparison

	Scenario A	Scenario B	Difference (B vs A)

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How the UK Mortgage Calculator works

A mortgage is likely the largest financial commitment you'll ever make — so it's worth understanding the numbers before you sign anything. This calculator shows your monthly repayment, total interest paid over the life of the loan, and a full month-by-month amortisation schedule so you can see exactly how your debt reduces over time.

Monthly repayments are calculated using the standard annuity formula: your outstanding balance, divided by the present value of an annuity at your interest rate and remaining term. In plain English: early payments are mostly interest; later payments are mostly capital. That's why overpaying early has such a dramatic effect — you're reducing the balance that interest is charged on.

The deposit you put down directly affects your Loan-to-Value (LTV) ratio, which in turn determines the interest rates lenders will offer. At 95% LTV (5% deposit) you'll typically pay significantly more than at 75% LTV (25% deposit). Every percentage point of deposit you can add tends to improve your rate, particularly at the key thresholds of 90%, 85%, 80%, and 75%.

Repayment vs interest-only

Most residential mortgages in the UK are repayment mortgages, where each payment reduces both the interest and the capital owed. At the end of the term your mortgage is fully paid off. Interest-only mortgages keep monthly payments lower because you're only paying the interest — but the original capital remains outstanding and must be repaid in full at the end. These are common for buy-to-let investors but require a credible repayment vehicle for residential use.

The real cost of a longer term

Stretching from a 25-year to a 35-year term cuts your monthly payment meaningfully — but the total interest paid over the life of the loan can increase by tens of thousands of pounds. Use the calculator to run both scenarios side-by-side. Even modest regular overpayments can shave years off your term and save significant amounts in interest, without the commitment of a shorter term from the outset.

What this calculator doesn't include

Stamp Duty Land Tax (SDLT), arrangement fees, valuation fees, solicitor costs, and buildings insurance all add to the true cost of buying a property. These vary considerably by property price and lender, so treat the calculator's output as the core mortgage cost — your mortgage adviser can give you a full picture of the upfront expenses.

UK Mortgage Calculator

Use this calculator to estimate your monthly mortgage repayments, total interest paid, and see a full amortisation schedule. Enter your property price, deposit, interest rate and term to get started.

How is a mortgage payment calculated?

Monthly repayments are calculated using the standard amortisation formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1] — where P = loan amount, r = monthly interest rate, n = total payments.

Example mortgage costs

£250,000 at 5% over 25 yearsMonthly payment: £1,461
Total interest: £188,347
Total repaid: £438,347

£350,000 at 4.5% over 30 yearsMonthly payment: £1,773
Total interest: £288,300
Total repaid: £638,300

LTV and how it affects your rate

Loan-to-Value (LTV) is the percentage of the property price you're borrowing. A lower LTV means lower risk for lenders and better rates for you. The key thresholds are 90%, 85%, 80%, 75% and 60% LTV. Saving to reach the next threshold can save you hundreds per month.