Mortgage Calculator
Quick Answer
Use our mortgage calculator to work out your monthly payments based on your loan amount, interest rate, and term. See exactly how much you'll pay each month and the total interest over the life of your mortgage. Adjust the figures to compare different scenarios.
Calculate Your Mortgage Payments
Per Bank of England analysis, small changes in rate or term can significantly affect both your monthly payment and total cost. This calculator shows you exactly what you'll pay—and helps you understand the trade-offs. To understand how much you can borrow, check our affordability calculator.
Set the loan, the rate, the term. Defaults are typical of a UK fixed-rate deal today.
£210,00084% LTV
Type
One payment, three truths. The big number is what hits your account each month. The other two are the long arc.
£1,167/ mo
monthly payment · over your term
In month one, £788 of your £1k is interest — only £380 reduces the loan. Over the term, you'll pay £140k to borrow £210k.
£350,174
loan + interest, paid back over the term
£140,174
67% extra on top of £210,000
Early on, most of your payment is interest. The split flips slowly, then quickly. The marker shows the year you've paid back half the loan.
By year 16, you've repaid half the loan. Most of the second half clears in the final five years — that's amortisation in action.
Small changes compound. A 0.5% rate difference, five extra years, an overpayment habit — each is worth tens of thousands.
Rate sensitivity
monthly payment at ±1% from your rate
3.5%
£1,051
-£116
4%
£1,108
-£59
4.5%
£1,167
yours
5%
£1,228
+£60
5.5%
£1,290
+£122
Term comparison
shorter term · higher monthly · less interest
- 20 yrs£1,329 / mo£109k interest+£161 / mo
- 25 yrs£1,167 / mo£140k interestyours
- 30 yrs£1,064 / mo£173k interest-£103 / mo
Overpayment dial
extra £/mo on top of the contractual payment
Drag the slider to see how much sooner you'd be mortgage-free.
The headline assumes a clean, uneventful 25 years. Reality has rate changes, fees, and surprises. Three things to keep in mind.
Your rate won't stay still
Most UK buyers remortgage every 2–5 years. After your fix ends, you'll either move to a new product or fall onto the lender's standard variable rate (typically 2–4% higher). Treat this calc as the picture of one deal, not the next 25 years.
Buildings insurance isn't included
Lenders require it; budget another £20–50/mo. Contents insurance is optional but most buyers get it.
Arrangement fees aren't in the monthly
Typical product fees are £0–£2,000, plus valuation £0–£500. Add legal fees of £800–£1,500. Compare offers on true cost, not headline rate.
Next step · Compare deals on true cost
Headline rate isn't everything. A 4% rate with £1,500 in fees can cost more than 4.25% with no fees. Use the comparison calculator to see total cost across the term.
Understanding Your Results
The calculator gives you three key figures. Here's what each one actually means for your finances.
Monthly Payment
This is what you'll pay each month throughout the mortgage term (assuming the rate stays constant). For repayment mortgages, this includes both interest and a portion of the loan itself.
Total Repayable
This is the total amount you'll pay over the entire mortgage term: the original loan plus all interest. On a typical mortgage, the interest portion often exceeds £100,000.
Total Interest Paid
This shows how much of your total repayments goes to interest rather than paying down the loan. It's often a sobering number—but understanding it helps you make informed decisions about overpayments and term length.
How We Calculate
The mortgage payment formula uses standard amortisation calculations.
For Repayment Mortgages
The monthly payment is calculated using:
M = P × [r(1+r)^n] / [(1+r)^n – 1]
Where:
- M = Monthly payment
- P = Principal (loan amount)
- r = Monthly interest rate (annual rate ÷ 12)
- n = Total number of payments (years × 12)
For Interest-Only Mortgages
Interest-only is simpler: you pay only the monthly interest.
M = P × (r ÷ 12)
At the end of the term, you still owe the full original loan amount.
Assumptions We Make
This calculator assumes:
- The interest rate stays constant throughout the term
- You make regular monthly payments
- No overpayments or underpayments
- The term runs its full course
According to UK Finance data, in reality, most people remortgage every 2-5 years when fixed terms end, so rates will change. Use this as a guide for your current deal, not a lifetime prediction. Learn more about choosing between 2-year and 5-year fixed mortgages.
Factors That Affect Your Payment
Understanding these variables helps you make better mortgage choices.
Loan Amount
Borrow more, pay more. A £10,000 increase in borrowing at 4.5% over 25 years adds roughly £56 to your monthly payment and £6,700 to total interest.
Interest Rate
Small rate differences compound significantly. Here's the impact:
| Rate | Monthly Payment (£250k/25yr) | Total Interest |
|---|---|---|
| 4.0% | £1,319 | £145,800 |
| 4.5% | £1,390 | £167,000 |
| 5.0% | £1,461 | £188,400 |
| 5.5% | £1,533 | £210,000 |
That 0.5% difference? It's £71 per month and over £21,000 in total interest.
Mortgage Term
Longer terms mean lower monthly payments but significantly more interest overall. Compare different mortgage types to find the best fit for your circumstances.
| Term | Monthly Payment (£250k at 4.5%) | Total Interest |
|---|---|---|
| 20 years | £1,582 | £129,600 |
| 25 years | £1,390 | £167,000 |
| 30 years | £1,267 | £206,000 |
| 35 years | £1,184 | £247,500 |
Extending from 25 to 30 years reduces your payment by £123 per month—but costs an extra £39,000 in interest.
Repayment vs Interest-Only
Interest-only payments are dramatically lower, but you don't reduce the loan.
For £250,000 at 4.5%:
- Repayment (25yr): £1,390/month, £0 owed at end
- Interest-only: £938/month, £250,000 still owed at end
Interest-only requires a separate plan to repay the capital.
What's Not Included
This calculator shows mortgage payments only. Your actual monthly housing costs include more.
Insurance Requirements
Lenders require buildings insurance. Most buyers also want contents insurance. Budget £20-50 per month.
Fees and Charges
Mortgage arrangement fees (£0-2,000), valuation fees (£0-500), and legal fees (£800-1,500) aren't included in the monthly payment but affect your total cost.
Rate Changes
Per Bank of England guidance, after your fixed period ends, you'll move to a new rate—either by remortgaging or falling onto the lender's SVR. This calculator shows one rate; reality involves changes over time.
Overpayments
If you plan to overpay, your actual term will be shorter and total interest will be lower. Most mortgages allow 10% overpayment per year without penalty.
Using This Information
The calculator is a tool for comparison and planning, not a final answer.
Comparing Scenarios
Try different combinations:
- What if you borrowed £20,000 less?
- What's the impact of a 0.25% rate difference?
- How does extending the term by 5 years affect things?
This helps you understand trade-offs and make informed decisions.
Budget Planning
Your mortgage payment is just one part of housing costs. A common guideline is that total housing costs (mortgage, insurance, maintenance) shouldn't exceed 35% of take-home pay.
The honest answer is that what's comfortable varies by individual. Some people happily spend 40%; others feel stretched at 30%. Know your own finances.
Rate Comparison
When comparing mortgage offers, the headline rate isn't everything. A 4.0% rate with £1,500 in fees might cost more than 4.25% with no fees, depending on your loan size and how long you keep the mortgage.
Lenders may include fees in their quoted payment, use slightly different calculation methods, or show APRC (annual percentage rate of charge) which factors in fees. This calculator shows the basic payment based on principal, rate, and term only.
For the inputs you provide, it's mathematically precise. However, it assumes constant rates and regular payments. Real mortgages involve rate changes, potential overpayments, and other variables. Use it for comparison and planning, not as a guarantee.
It depends on your priorities. Longer terms reduce monthly payments but increase total interest significantly. If affordability is tight now but you expect income growth, starting longer and overpaying later can work. If you can comfortably afford shorter-term payments, you'll save substantially on interest.
Next Steps
With a clear picture of your potential payments, you're better equipped to search for properties within budget and compare mortgage offers effectively.
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