Mortgage Calculators
Interest-Only Mortgage Calculator
Compare the payment during an interest-only period with the repayment that follows once capital repayment begins.
Interest-only payment
$1,750.00
- Payment afterwards
- $2,255.05
- Payment increase
- $505.05
- Total interest over the term
- $431,516
How this calculator works
Interest-only payment = P × r; later payment amortises P over the remaining term
- P
- the loan amount, unchanged during the interest-only period
- r
- the monthly interest rate
Example calculation
Illustrative example — not advice
Worked example — the interest-only mortgage calculator as it loads, using the default figures below.
- 01Enter loan amount: $350,000.
- 02Enter interest rate: 6%.
- 03Enter interest-only period: 5 years.
- 04Enter total term: 30 years.
- 05Read the interest-only payment from the results panel: $1,750.00.
Interest-only payment: $1,750.00. Payment afterwards: $2,255.05. Payment increase: $505.05. Total interest over the term: $431,516.
These figures come straight from the calculator above running on the values listed, so you can retype them and confirm every number yourself. Change any input and the results update immediately. Illustrative only — not a quote, offer or recommendation.
Important considerations
- The balance does not fall at all during the interest-only period.
- The payment jump at the end is the main risk — model it before committing.
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Terms used here
Frequently asked questions
Why is interest-only cheaper at first?
Because you are not repaying any capital, so the balance and the interest on it stay the same.
Disclaimer
Legamoney calculators are educational tools. Results are estimates based on the figures you enter and do not constitute financial, tax or legal advice.
Last reviewed 2026-08-01