Irish Calculators
Loans & mortgages

Buy-to-Let Mortgage Repayment Calculator

Calculate debt service for a rental-property mortgage using your supplied financing terms. Rental income, tax, profitability and lender approval are separate from this repayment estimate.

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Your numbers

%
Monthly interest is the annual nominal rate divided by 12. This is not a fee-inclusive APR.
Your figures stay on this device.

How the calculation works

Estimate repayment debt service for a buy-to-let purchase from price, deposit, rate and term. The tool models a conventional amortising mortgage, with upfront finance fees kept separate from principal.

Mortgage principal = property price − deposit; repayment uses the monthly annuity formula. Upfront fees are separate cash costs.

  1. Calculate borrowing

    Subtract deposit from purchase price. This gives principal to amortise; the result does not determine whether a lender will approve that borrowing.

  2. Calculate debt service

    Apply the monthly annuity formula using principal, rate and term. At zero interest, payment equals principal divided by months.

  3. Separate fees and interest

    Compare repayment total with principal to identify interest. Add upfront fees to repayment cash cost, keeping the original purchase deposit separate.

Worked example: Deposit deducted once

Sample inputs demonstrate the method. They are not a forecast or product offer.

A €10,000 price less €2,000 deposit leaves €8,000 borrowing. At zero interest over eight months, payment is €1,000. Adding €100 upfront fees gives €8,100 in repayments plus fees, excluding the purchase deposit.

Property purchase price
10000
Deposit
2000
Annual nominal interest rate (%)
0
Remaining term (months)
8
Upfront finance fees
100

Expected result

Monthly repayment
€1,000.00
Mortgage principal
€8,000.00
Payments plus upfront fees
€8,100.00
Worked example: One-month interest

Sample inputs demonstrate the method. They are not a forecast or product offer.

Property purchase price
1000
Deposit
200
Annual nominal interest rate (%)
12
Remaining term (months)
1
Upfront finance fees
0

Expected result

Monthly repayment
€808.00
Interest over term
€8.00

Understanding your result

This is a financing calculation, not a property-profitability assessment. Rent, vacancy, repairs, management costs and tax have not been used to decide whether the investment earns a profit.

Compare debt service with a separately calculated net rental cash-flow allowance rather than assuming all gross rent is available. Rental income is not estimated by this form.

Questions you might have

Does rent cover this payment?

Compare the payment with your net rental cash flow after vacancy and property costs, not with gross rent alone.

Choosing the right inputs

Property purchase price
Enter property purchase price, not the mortgage amount. The deposit is subtracted to calculate borrowing, so entering principal here would deduct it twice.
Deposit
Use the deposit applied to the purchase. Other acquisition charges are not automatically financed or included in this field.
Annual nominal interest rate
Supply an annual nominal rate from your scenario or quote. Monthly interest is one twelfth of this rate, not an inferred fee-inclusive APR.
Upfront finance fees
Enter finance fees paid upfront. They enter the cash-cost total but are not silently capitalised into the mortgage balance.

Common mistakes to avoid

  • Do not interpret the output as a required deposit, lender affordability test or available interest rate.
  • Do not count the same finance fee within borrowed principal and again as a separate cash charge.

Assumptions to check

  • This estimates debt service only; it does not infer rental income, tax, profitability or lending approval.

Sources and method

Read our calculation and testing approach.