A £100,000 mortgage in the UK costs between £477 and £644 per month on a standard repayment basis, depending on your interest rate and loan term. At a representative interest rate of 4.5%, you will pay £556 per month on a 25-year term or £507 per month on a 30-year term.
Whether you are buying a first property, downsizing, or remortgaging an existing balance, understanding your exact monthly repayment and long-term interest cost is essential. You can model different interest rates, loan terms, and deposit amounts with the mortgage repayment calculator. If you are assessing whether to purchase or continue renting, the rent vs buy calculator projects the long-term financial outcome of each choice.
Monthly repayments at 4% to 6% interest
The tables below display the exact monthly repayment and total interest payable on a £100,000 capital and interest repayment mortgage across five common interest rates.
Monthly repayments over 25 years
On a traditional 25-year term (300 monthly payments), repayments and total borrowing costs are:
| Interest Rate | Monthly Payment | Total Interest Paid | Total Repaid |
|---|---|---|---|
| 4.0% | £528 | £58,351 | £158,351 |
| 4.5% | £556 | £66,750 | £166,750 |
| 5.0% | £585 | £75,377 | £175,377 |
| 5.5% | £614 | £84,226 | £184,226 |
| 6.0% | £644 | £93,290 | £193,290 |
At 4.5% over 25 years, you pay £556 each month. Over the lifetime of the mortgage, you repay the original £100,000 capital alongside £66,750 in interest, bringing the total sum paid to £166,750.
Monthly repayments over 30 years
Opting for an extended 30-year term (360 monthly payments) lowers your monthly payment obligation:
| Interest Rate | Monthly Payment | Total Interest Paid | Total Repaid |
|---|---|---|---|
| 4.0% | £477 | £71,869 | £171,869 |
| 4.5% | £507 | £82,407 | £182,407 |
| 5.0% | £537 | £93,256 | £193,256 |
| 5.5% | £568 | £104,404 | £204,404 |
| 6.0% | £600 | £115,838 | £215,838 |
Extending the term from 25 to 30 years at 4.5% reduces the monthly bill from £556 to £507, saving £49 per month. However, that extra five years adds £15,657 in interest charges over the life of the loan.
Comparing 25-year and 30-year mortgage terms
Choosing between a 25-year and 30-year mortgage requires balancing immediate cash flow against overall financial cost:
- Monthly cash flow: A 30-year term provides lower monthly payments, which can help first-time buyers satisfy lender affordability assessments or maintain financial breathing room.
- Total interest outlay: Because the loan balance declines more slowly, interest accumulates over an additional 60 months. At 5.0% interest, a 30-year mortgage incurs £93,256 in interest, compared to £75,377 on a 25-year mortgage.
- Flexibility: Many borrowers select a 30-year term for safety and make contractual overpayments of £50 to £100 each month. This strategy achieves the rapid repayment schedule of a 25-year loan while retaining the contractual option to pause extra payments if household expenses rise.
Interest-only repayments on a £100,000 loan
On an interest-only mortgage, you pay only the monthly interest charge. The £100,000 principal balance remains unchanged throughout the term and must be repaid as a lump sum at the end:
- 4.0% interest: £333 per month (£4,000 per year)
- 4.5% interest: £375 per month (£4,500 per year)
- 5.0% interest: £417 per month (£5,000 per year)
- 5.5% interest: £458 per month (£5,500 per year)
- 6.0% interest: £500 per month (£6,000 per year)
Interest-only mortgages are standard in the buy-to-let property market, but residential mortgage lenders require a verified repayment vehicle, such as an investment portfolio, pension lump sum, or sale of another property.
Salary required for a £100,000 mortgage
Under Financial Conduct Authority mortgage lending regulations, UK lenders cap standard borrowing at 4.0 to 4.5 times gross household annual income:
- At 4.5 times income, you need a gross annual salary of £22,222 to borrow £100,000.
- At 4.0 times income, you need a gross annual salary of £25,000 to borrow £100,000.
- At 3.5 times income, you need a gross annual salary of £28,571 to borrow £100,000.
In the 2026/27 tax year, a single earner on £25,000 has a personal allowance of £12,570. After standard basic rate income tax of 20% (£2,486) and employee National Insurance of 8% (£994), take-home pay is approximately £21,520 per year, or £1,793 per month. A monthly mortgage payment of £556 represents 31% of net monthly income, which falls well within standard UK affordability guidelines.
How overpayments save thousands in interest
Making regular overpayments directly against the mortgage principal dramatically reduces total interest and cuts years off the term.
For example, on a £100,000 mortgage at 5.0% over 25 years with a standard monthly repayment of £585:
- Overpaying £50 per month: Total payment £635 per month. You clear the mortgage 3 years and 4 months early, saving £11,850 in interest.
- Overpaying £100 per month: Total payment £685 per month. You clear the mortgage 5 years and 11 months early, saving £20,320 in interest.
Most UK fixed-rate mortgage lenders permit overpayments of up to 10% of the outstanding balance each year without incurring early repayment charges. You can explore how extra payments shorten your mortgage on the mortgage repayment calculator.
Frequently asked questions
What income do you need to borrow a £100,000 mortgage?
Most UK mortgage lenders offer up to 4.5 times your gross annual income, subject to credit checks and outgoings. To borrow £100,000, you generally need an individual or combined household income of at least £22,222 to £25,000 per year.
How much total interest do you pay on a £100,000 mortgage?
The total interest paid depends on your interest rate and loan duration. Over a 25-year term at 4.5% interest, you will pay £66,750 in interest. If the rate is 5.5%, total interest increases to £84,226. Extending the loan term to 30 years at 5.5% increases total interest to £104,404.
Is it better to choose a 25-year or 30-year mortgage term?
A 25-year mortgage costs significantly less in total interest and clears your debt five years sooner. A 30-year mortgage offers lower required monthly repayments, which can help with affordability assessments. Many borrowers choose a 30-year term and make voluntary overpayments when cash allows.
What happens when a fixed-rate mortgage deal ends?
When a fixed-rate product expires, the loan automatically transfers to your lender standard variable rate (SVR), which is often 2% to 4% higher than competitive fixed rates. Most borrowers remortgage to a new fixed or tracker deal three to six months before their current product concludes.