Loan-to-value (LTV)
The calculator applies a fixed percentage to the property's purchase price or valuation to estimate the maximum mortgage amount.
BUY-TO-LET MORTGAGE CALCULATOR
Estimate Your Maximum Buy-to-Let Mortgage Borrowing
Understanding how much you may be able to borrow against rental property is an important first step in assessing a buy-to-let investment opportunity. Our Buy-to-Let Mortgage Calculator provides a quick estimate based on the property's estimated purchase price or valuation, together with the property type you select (standard Buy-to-Let or HMO). It can help you gauge the maximum loan amount that may be available and understand the loan-to-value position of the proposed borrowing. The results are estimates only. The mortgage amount, interest rate, and products available will depend on your circumstances, the property, expected rental income, and the lender's criteria.
Your property may be repossessed if you do not keep up the repayments on your mortgage.
Estimate Your Buy to Let Borrowing
What's the application type?
What's the Interest Cover Ratio (ICR)?
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Please note: Results generated by this calculator are estimates only. They do not constitute mortgage advice, a recommendation, a formal quotation, or a mortgage offer.
About This Calculator
What Is a Buy-to-Let Mortgage Calculator?
A buy-to-let mortgage calculator helps you estimate how much you may be able to borrow against a property you intend to rent out. This calculator takes a simplified approach by applying a fixed loan-to-value percentage to the property’s purchase price or valuation. It does not perform a full Interest Coverage Ratio (ICR) stress test using the rental income figure instead; it provides a quick LTV-based estimate that can be used as an initial guide.
The calculator can help you:
Estimate the maximum loan based on the property value
Understand the property's loan-to-value position
Compare different property values and property types (BTL vs HMO)
Get a quick initial indication before speaking to a broker
It can be used as a starting point for both purchases and remortgages.
Borrowing Estimate
How Much Could You Borrow?
The amount the calculator estimates is based on a single calculation:
For example, if a property is valued at £250,000 and the calculator applies 85% LTV for a standard Buy-to-Let, the estimated maximum loan would be £212,500. The calculator does not apply for a rental income stress test.
In practice, lenders will also assess whether the expected rent is sufficient to cover the mortgage of interest by the required Interest Coverage Ratio (ICR). The actual maximum mortgage may therefore be the lower of:
The amount indicated by this LTV-based calculator
The amount supported by the rental income under the lender’s ICR criteria.
Worked Example
Buy-to-Let Calculation Example
The following example is for illustration only.
Property typeStandard Buy-to-Let (BTL)
Property value£250,000
LTV applied85%
Estimated maximum loan£212,500
Required deposit£37,500 (15%)
Property type(House in Multiple Occupation)
Property value£250,000
LTV applied80%
Estimated maximum loan£200,000
Required deposit£50,000 (20%)
LTV & Deposits
Understanding Loan-to-Value & Deposit Requirements
Loan-to-Value (LTV)
Loan-to-value, or LTV, compares the mortgage amount with the property's value. It is generally calculated as:
Mortgage amount / Property value X 100
For example, borrowing £212,500 against a property valued at £250,000 would represent 85% LTV.
A larger deposit reduces the LTV and the amount borrowed. It may also provide access to a wider selection of mortgage products and more favorable rates, subject to lender criteria.
Rental Income
The Role of Rental Income in This Calculator
The calculator includes a field for “estimated monthly rental income.” This field is not used in the actual calculation. The estimated maximum loan is derived solely from the property value and the selected property type. In a full lender assessment, rental income is critical. Lenders apply for an Interest Coverage Ratio (ICR) stress test to ensure the rent comfortably exceeds the mortgage interest payment at a notional higher rate. This calculator provides an LTV-based estimate only and does not model for the ICR test.
Interest Coverage Ratio
Interest Coverage Ratio (ICR) What the Calculator Does Not Show
Lenders use different stress rates depending on the mortgage product, initial rate period, property type, and application. The stress rate may be based on the product rate, a minimum reference rate, or the higher of several figures. The standard ICR requirements are:
For example, at 5.5% stress rate and 125% ICR:
Maximum Loan = (Monthly Rent x 12) / (0.055 x 1.25)
Maximum Loan = (Monthly Rent x 12) / 0.06875
Maximum Loan = Monthly Rent x 174.55
This means a monthly rent of £1,000 could theoretically support a loan of approximately £174,550 under the ICR test, but the actual maximum would also be constrained by the lender's maximum LTV.
Rental Yield
Understanding Rental Yield
Gross rental yield compares the property's annual rent with its value. It is generally calculated as:
For example, a property valued at £250,000 with expected monthly rent of £1,250 would generate £15,000 in gross annual rent: £15,000 ÷ £250,000 × 100 = 6% gross rental yield Gross yield does not show the actual return from the property because it does not deduct mortgage payments, tax or other expenses.
Costs
Costs Not Included in the Calculator
The calculator estimates the maximum loan amount only. It does not provide a complete picture of the cost of owning a rental property. You may also need to budget for:
- Stamp Duty Land Tax or the relevant property transaction tax
- Mortgage product and arrangement fees
- Valuation and legal fees
- Buildings and landlord insurance
- Letting agent and management fees
- Repairs, maintenance and safety checks
- Service charges and ground rent, where applicable
- Property licensing costs
- Periods when the property is unoccupied
- Rent arrears or unpaid rent
- Tax and accountancy costs
Tax treatment depends on individual circumstances and may change. Appropriate tax and legal advice should be obtained where required.
Cost Difference
Why the Actual Amount May Differ
The calculator uses a simplified LTV model to provide an estimate. The actual mortgage amount available may be affected by:
- The expected rental income and the lender's ICR stress test
- The interest rate offered
- The property's valuation, type and condition
- The deposit and loan-to-value ratio
- Your credit profile and financial circumstances
- Whether the property is owned personally or through a limited company
- Product fees added to the mortgage
- Whether the lender offers top slicing (using personal income to bridge a rental shortfall)
Repayment Method
Interest-Only or Repayment?
The calculator does not distinguish between interest-only and capital repayment methods. In practice:
Interest-Only Mortgage
The monthly payment normally covers only the interest charged. This can result in a lower monthly payment, but it does not reduce the original mortgage balance. You will need a credible repayment strategy to repay the capital at the end of the term.
Repayment Mortgage
Each monthly payment covers the interest and repays part of the original loan. The monthly payment will normally be higher than an equivalent interest-only mortgage, but the balance should be repaid by the end of the term. The appropriate repayment method will depend on your circumstances, objectives, and the lender's criteria.
FAQ's
Frequently Asked Questions
Yes. You can use the calculator without charge or obligation.
Personalised Advice
Speak to an adviserNeed More Than an Estimate?
A Buy-to-Let Mortgage Calculator is a useful starting point, but choosing a mortgage involves more than comparing the property's value with the maximum LTV. Rental income requirements, mortgage fees, property type, ownership structure and your longer-term plans may all affect which options are available. An adviser can help you explore buy-to-let mortgage products and understand the potential borrowing costs based on your full circumstances.
Your property may be repossessed if you do not keep up the repayments on your mortgage.
Not all buy-to-let mortgages are regulated by the Financial Conduct Authority.