Semi-commercial mortgage calculator
This semi-commercial mortgage calculator will estimate monthly repayments and rent cover on a mixed-use property from your own figures. The calculator is coming soon; the guide below explains each input.
Reviewed by David Sampson, Founder & Director · Created 20 October 2026 · Last reviewed 20 October 2026
What will the semi-commercial mortgage calculator show?
A semi-commercial mortgage calculator estimates the monthly repayment and total interest on a loan for a mixed-use building, such as a shop with flats above. Enter the price, deposit, interest rate and term, then the rent from the commercial and residential parts, to see how far the rent covers the interest.
Every figure will be an input, so the result reflects the numbers entered rather than market data. It is a planning estimate, not a quote or a lending decision. How mixed-use lending works is explained in the mixed-use mortgages section.
The inputs explained
The loan is the price less the deposit. The rate should come from a quote or illustration, and the term is the number of years agreed with the lender. Repayment loans reduce the balance over the term, while interest-only loans keep it the same and need a plan to repay the loan at the end.
The rent is entered in two parts, the commercial lease and the residential tenancies, because lenders look at each. Lenders use their own valuation and their own view of the rent, so their figures may differ from those entered.
The term affects both the monthly payment and the total cost. A longer term lowers the payment but increases the interest paid overall. Pricing for mixed-use property is explained on the semi-commercial mortgage rates page.
Using the result
The result helps set a budget and compare options before speaking to a lender. Testing a higher rate, a lower rent or an empty shop shows how sensitive the loan is to change. Stamp duty, valuation and legal fees are not included and need to be added to see the full cost of buying.
Until the calculator is live, the same sums can be worked out by hand. Interest-only cost is the loan multiplied by the annual rate, and rent cover is the annual rent divided by that cost. A broker can quote current pricing for a specific case.
Frequently asked questions
How do I calculate a semi-commercial mortgage repayment?
For interest-only, multiply the loan by the annual rate and divide by twelve. A repayment loan costs more each month because part of each payment reduces the balance.
Is the semi-commercial mortgage calculator live?
Not yet. The calculator is coming soon. The guide on this page explains how each input works.
What is rent cover?
The annual rent divided by the annual interest. Lenders set their own minimum.
Does the calculator work for a flat above a shop?
Yes. Enter the rent from the shop and the flat separately.
Does the result include stamp duty?
No. Stamp duty, valuation and legal fees are extra costs to add.
Is the result a mortgage offer?
No. It is an estimate from the figures entered. Only a lender can make an offer.
Important: Your home may be repossessed if you do not keep up repayments on your mortgage. Information on this page is for general guidance only and does not constitute financial advice.Always verify details directly and seek independent advice before making financial decisions.