Self Build Mortgage Calculator
A Self-Build Mortgage Calculator helps you estimate how much you’ll repay monthly based on the different loan stages, the amount borrowed in each stage, and the interest rate applied. It’s useful if you’re planning a self-build and want to budget your repayments more accurately throughout the build.
A self-build mortgage is a type of home loan specifically designed for people who want to build their own home, rather than buy an existing one. Instead of receiving the full loan amount upfront, the money is released in stages, called tranches, as your building project progresses.
How Does the Calculator Work?
- Break the Loan into Tranches: Select each building stage (like Land Purchase, Substructure, Roof Tiling, etc.).
- Enter Amounts: Input how much you’ll need to borrow at each stage.
- Add Interest Rate: Enter the expected interest rate for each tranche.
- View Monthly Repayments: The calculator shows your monthly repayment per tranche and a total monthly figure.
For example, if you borrow:
- £150,000 at 4% for Land Purchase
- £50,000 at 5% for Substructure
- £100,000 at 5% for Wallplate/eaves height
Your monthly repayment will be:
£500 + £208.33 + £416.67 = £1,125.00
You can add more stages like Roof Tiling, Final Payment, or First Fix using the “Add Tranche” option.
What Is the Calculator Used For?
- Budget Planning: Helps you understand your cash flow during different build phases.
- Loan Management: See how borrowing in parts affects your repayments.
- Decision-Making: Compare how changing loan amounts or interest rates affects your costs.
It’s a great tool for anyone planning a custom home build who wants a clearer picture of the costs involved throughout the project.