Mortgage Calculator

Compare interest-only and repayment mortgage payments, interest and loan-to-value. Interest-only payments leave the capital due at term. The result updates as you type so you can compare scenarios quickly.

The method

How it is worked out

Interest only: monthly payment = P × i
Repayment: monthly payment = P × i × (1 + i)^N(1 + i)^N − 1

P: Price minus deposit
i: Monthly rate, annual ÷ 12
N: Months in the term

Keep in mind

What it leaves out

Buying costsclosing costs and transfer taxes, legal fees, surveys and insurance aren't included.
Rate changesFixed deals end. Your rate will likely change during the term.
Interest-only capitalMonthly interest-only payments do not reduce the capital. You need to repay it at the end of the term.

Use the calculator to compare scenarios rather than as a guaranteed forecast.

About the Mortgage Calculator

Use the Mortgage Calculator before comparing a home loan or remortgage. Enter the property price, deposit, interest rate and term, then choose interest-only or repayment. It shows the monthly payment and loan-to-value so you can weigh the cash you need each month against the debt remaining at the end.

How it works and an example to tryShow less

How to use the result

The loan is the property price less the deposit. Interest-only mode charges interest on that balance each month and leaves the entire capital outstanding. Repayment mode spreads capital and interest over monthly payments, reducing the balance over time. Both modes hold the annual rate constant; neither includes legal fees, insurance or a change of rate when a deal ends.

Example to try

Try a property priced at 280,000 with a 28,000 deposit over 30 years at 4.8%. Compare the default interest-only payment with a repayment mortgage. Look at the remaining balance at the end of the term as well as the monthly figure before judging which arrangement you could afford.

Put it to work

Try it on a real situation

Load an example

What moves the result most

Worked out from your figures above. Tap a row to try it.

Who uses it, and when

First-time buyers weighing what they can afford each month, homeowners deciding whether to remortgage when a fixed deal ends, and landlords comparing interest-only against repayment on a rental property. Mortgage brokers also use it to give a client a quick, honest first figure before a full affordability check.

Mistakes worth avoiding

Comparing an interest-only payment with a repayment payment and forgetting the whole loan is still owed at the end of the interest-only term.
Using the headline rate on a two-year deal as if it lasts for the full 25 or 30 years.
Leaving out closing costs and transfer taxes, valuation, legal and arrangement fees, which can add several thousand to the cash you need up front.

Questions

What does the Mortgage Calculator do?

Compare interest-only and repayment mortgage payments, interest and loan-to-value. Interest-only payments leave the capital due at term.

How should I use the result?

Does TechBullion store the information I enter?

The core calculation or transformation runs in your browser. Normal website security and analytics may still record page-level events, but the tool does not need to create a public record from your inputs.

What mistakes do people make with a mortgage calculator?

Comparing an interest-only payment with a repayment payment and forgetting the whole loan is still owed at the end of the interest-only term. Using the headline rate on a two-year deal as if it lasts for the full 25 or 30 years. Leaving out closing costs and transfer taxes, valuation, legal and arrangement fees, which can add several thousand to the cash you need up front.

Is the result guaranteed?

No. Use the result as a practical check or planning aid and verify important decisions with the relevant primary source, provider or professional advice.

Continue with TechBullion Tools