Buy-To-Let Mortgage Calculator

As a buy-to-let investor, a solid grasp of your numbers can be the difference between making a profit or not.

Use our buy-to-let mortgage calculators to get an in-depth insight into the numbers that matter.

From calculating your mortgage payments to calculating your return on investment, we have a calculator to help.

Call us – 01604 212879

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Work out all your buy-to-let costs with our range of helpful calculators

Speak To A Buy To Let Mortgage Expert

  • Free no-obligation advice
  • Find out how much you can borrow
  • Advice on enhanced stress rates
  • ZERO broker fees to pay – ever

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About Our Buy-To-Let Mortgage Calculator

You can use our range of calculators to crunch the numbers on how profitable your next buy-to-let investment might be and how much you can borrow.

Calculating how much can be borrowed can be complex due to different lenders using different product stress rates. Use our max borrowing calculators to give you some initial guidance but it’s always best to speak to an adviser, who will be able to better advise of your options.

Calculate your buy-to-let monthly repayments

Use this calculator to understand your monthly repayments on an interest-only or capital repayment basis. Just enter the loan amount, interest rate and term and we’ll calculate your monthly payments. If you wish, you can also add any potential lender fees to the loan to calculate the additional cost for doing so.

Interest only mortgages

The most common repayment type for buy-to-let mortgages. You pay the interest on the loan only. To find out more, read our interest-only buy-to-let mortgage guide.

Capital Repayment Mortgages

With this type of mortgage, you repay the interest plus some of the capital each month. You are guaranteed to repay your mortgage at the end of the term if you maintain your payments.

Adding Lender Fees

You can check the box to calculate how much extra your mortgage payment will be by adding any lender fees to the loan. By adding fees to the loan, you’ll pay interest on that fee for the loan term, and it will increase your overall LTV.

Calculate maximum loan amount or rental income required

Use this calculator to work out how much you can borrow based on the rental income, or what the rental income needs to be to achieve a specific loan amount.

Calculating affordability for a buy-to-let mortgage is based on several factors, including the rental income, the type of product selected, the chosen rate, and whether an individual or limited company will own the property. You can learn more about calculating buy-to-let affordability with our guide to rental stress testing.

Interest Cover Ratio (ICR)

The property owner determines the ICR, which is the ratio by which the rental income needs to cover the ‘stressed’ mortgage payment; for example, if the stressed payment is £1000pm, and the ICR is 125%, then the rental income needs to be a minimum of £1250pcm. (£1000 * 125%)

Initial Product Term

The term of the product chosen will determine the ‘stress’ rate the lender applies. A 5-year fixed or longer will normally be stressed at the actual rate you pay, known as the ‘pay rate’. Products of less than 5 years will be stressed more harshly, with most lenders currently using the rate selected, plus a margin of up to 2%, so if you opt for a 2-year fixed @ 5%, the stress rate will be 7%. The higher the stress rate, the less you can borrow. The margin applied to shorter-term products will vary from lender to lender and could be less than 2%, but for the purposes of our calculator, we use a margin of 2%.

Interest Rate Selected

Use this field to enter the rate of the product of interest. If it’s a 5-year fixed, our calculator will use that rate as the stress rate.

If it is a product of less than 5 years, such as a 2-year fixed or tracker rate, our calculator will use the rate entered plus 2%. It’s essential to note that stress tests will vary from lender to lender, and this calculator is for guidance only.

Top Slicing

Top slicing is a feature some lenders offer that allows the use of personal income to support a loan requirement in the event of a shortfall based on the rental income. Call us to see how top slicing could help. 

Call us on 01604 212879 for a no obligation buy to let mortgage review

Calculate Yield and Return On Investment (ROI)

Use this calculator if you wish to calculate the yield on your buy to let investment, or to calculate your return on investment.

Yield on a buy-to-let property can help you understand what return you will get on your investment. Rental yield is a calculation expressed as a percentage that indicates the return on the rental income taking into account the property value.

Return on Investment, or ROI, is the annual pre-tax profit generated by your buy-to-let investment, divided by the cash you have invested into the property. The ROI calculation does not take tax into account.

ROI can also be referred to as Return On Cash (ROC) or Return On Capital Employed (ROCE). It is effectively just a measure of the return from the money you have put into the property yourself (deposit).

Gross Yield

Gross yield is the simplest calculation as all it takes into account is the annual rental income and the property value. It does not include any other expenses associated with the investment.

Net Yield

Net yield takes into account all of the expenses associated with a buy-to-let investment, and can provide a more accurate calculation of the expected yield.

ROI Calculation

The calculation for ROI is the profit from the annual rental income after deduction of costs, divided by the cash invested.

For example:

  • Annual Rental Income – £12,000
  • Annual Costs – £7500 (mortgage, insurance, fees etc)
  • Annual Profit – £4500 (£12,000 Income – £7500 Costs)
  • Cash Invested – £75,000

ROI would be 6%

(£4500 / £75,000 * 100)


Thanks for using our buy-to-let mortgage calculator

Whilst you are here, why not take a look at some of our other buy-to-let pages below for further information

Find out more about buy to let mortgages

Do you have bad credit? Find out how we can help with our bad credit buy-to-let mortgages.

If you are thinking about letting your current property, you may need a let-to-buy mortgage.

Find out more about Limited Company BTL Mortgages

Need a better yield? Find out more about HMO Mortgages and Multi-Unit Block Mortgages.


A small selection of some of our Buy-To-Let Mortgage Lenders

We source our mortgages from the whole market, from the leading High St Banks & Building Societies to specialist buy-to-let mortgage lenders. A selection of our lenders is shown below.