If you like the idea of an interest-only mortgage, but don’t want to be saddled with repaying your full loan amount in 25 years time, a part and part, or hybrid mortgage, could be a good middle ground. You can use our part and part calculator to work out what your monthly repayments would look like if you split your debt between capital repayment and interest-only.
What is a Part and Part Mortgage?
A part-and-part mortgage is a hybrid agreement where one portion of your loan is set up as a capital repayment mortgage and the remaining portion is interest-only.
This structure allows you to benefit from the lower monthly payments associated with interest-only mortgages while ensuring that at least some of the capital debt is being cleared every month. It is often seen as a middle ground for borrowers who want to reduce their monthly outgoings without leaving the entire loan balance to be paid as a lump sum at the end of the term.
How this calculator works
Our part-and-part calculator takes your total loan requirements and splits the interest calculation accordingly:
- The repayment element: It calculates the monthly cost to cover both interest and a portion of the principal for the amount you’ve specified
- The Interest-only element: It calculates the interest due on the remaining balance, which remains static throughout the term
- Total monthly cost: It combines these two figures to give you a single monthly repayment estimate
- Total interest paid: The total interest you will pay over the full mortgage term (this does not take into consideration any remortgages)
- How it compares: The calculator also shows you how the same mortgage would compare if taken out on an a full repayment basis and a full interest-only basis
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Example Part and Part Calculations
This table shows how a part-and-part mortgage compares to other repayment types. It is based on a £250,000 mortgage at a 4% interest rate over 25 years:
|
Mortgage Type |
Repayment element |
Interest-only element |
Estimated monthly payment |
Lump sum repayment at end of mortgage |
|
Full Repayment |
£250,000 |
£0 |
£1,320 |
£0 |
|
Part-and-Part |
£125,000 |
£125,000 (50% split) |
£1,076 |
£125,000 |
|
Full Interest-Only |
£0 |
£250,000 |
£833 |
£250,000 |
Comparison of part-and-part splits
Seeing how the dial shifts between lower monthly cost and lower final debt is crucial to your decision on how to best split your hybrid mortgage.
While it’s important to consider the immediate monthly savings when using any percentage of interest-only mortgage repayment, it’s also important to keep in mind that as well as having to repay the outstanding balance at the end of the mortgage term, you will pay significantly more interest over the full mortgage term.
This table shows the impact of various splits on your monthly repayments, as well as the total interest payable and your final balance, based on a £250,000 mortgage at a 4% interest rate over a 25-year term:
|
Repayment / IO Split |
Monthly Payment |
Total Interest Paid (25 yrs) |
Final Balance Owed |
|
90 / 10 Split |
£1,271 |
£156,285 |
£25,000 |
|
85 / 15 Split |
£1,247 |
£161,492 |
£37,500 |
|
75 / 25 Split |
£1,198 |
£171,905 |
£62,500 |
|
60 / 40 Split |
£1,125 |
£187,524 |
£100,000 |
|
50 / 50 Split |
£1,076 |
£197,936 |
£125,000 |
|
25 / 75 Split |
£955 |
£223,968 |
£187,500 |
|
15 / 85 Split |
£906 |
£234,382 |
£212,500 |
|
10 / 90 Split |
£882 |
£239,588 |
£225,000 |
Note: The figures presented in these tables are for illustrative purposes only. Actual rates and terms will depend on lender criteria and your personal circumstances.
Which split is right for you?
-
The 75/25 or higher repayment/Interest-only split: Ideal for those who want to pay off the vast majority of their home monthly during the mortgage term, but need an extra £120+ in their pocket every month for other investments or living costs
-
The 50/50 Split: The classic hybrid. It offers a significant monthly saving (£244/month) while ensuring you only have to find half of the capital at the end of the term
-
The 25/75 or lower repayment/interest-only split: Best for borrowers with a guaranteed future windfall (like a pension lump sum or inheritance) who need maximum cash flow today
Why choose a part-and-part mortgage?
There are several scenarios where a hybrid mortgage might be the most effective choice for a homeowner:
-
Lower monthly costs: By keeping a portion of the loan on an interest-only basis, your monthly commitment is lower than a full capital repayment mortgage
-
Managing debt: Unlike a pure interest-only mortgage, you are actively chipping away at the debt, meaning the final lump sum you owe at the end of the term will be smaller
-
Affordability: This can be a useful tool for buyers who expect their income to rise in the future but need lower payments in the short term
-
Flexibility: Many lenders allow you to choose the split (e.g., 50/50 or 75/25) based on your specific repayment vehicle or budget
Secure your part-and-part mortgage today
Navigating the middle ground between interest-only and capital repayment can be complex. While our calculator provides a clear estimate, speaking with a specialist broker ensures you choose the right split for your financial future. Whether you’re looking to lower your monthly bills or find a flexible way to manage your mortgage, our experts are here to help. We search the whole of the market to find the most competitive part-and-part deals available.
Get started to speak to one of our hybrid mortgage specialists.