How is a mortgage repayment calculated?

Monthly repayment = P × r(1+r)^n / ((1+r)^n − 1), where P is loan amount, r is monthly rate (annual ÷ 12), and n is total months.

How do extra repayments reduce my mortgage?

Extra repayments reduce your principal balance directly, lowering the interest each month. This saves significant interest and cuts years off your term.

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Your mortgage repayment, calculated for any country

Switch between Australia, USA, UK, New Zealand, Canada, and Singapore. See monthly repayments, total interest, transfer taxes, and the impact of extra repayments.

💡At 6.5% over 30 years — total interest: A$765,267

Used by 50,000+ users monthly · No sign-up required · Instant results

Monthly repayment

A$3,792

Principal & Interest

Total interest

A$765,267

Over 30 years

Total paid

A$1,365,267

P&I over full term

Deposit

A$150,000

20% of price

Stamp duty (NSW est.)

A$28,485

Est. transfer tax

Total upfront

A$178,485

Deposit + tax

💡

Try adding extra repayments — even could save you approximately A$240,674 in interest.

Annual payment breakdown

PrincipalInterest

Quick comparison — A$750,000 at current deposit

🇦🇺Australia (6.5% / 30yr)A$3,792/mo

🇺🇸United States (7% / 30yr)$3,992/mo

🇬🇧United Kingdom (5% / 25yr)£3,508/mo

🇳🇿New Zealand (7.2% / 30yr)NZ$4,073/mo

The repayment formula

M = P × r(1+r)^n
÷
(1+r)^n − 1

MMonthly payment

PLoan amount

rMonthly rate (annual ÷ 12)

nTotal months

Country-specific notes

For Australia-specific details including state stamp duty, LMI thresholds, and first home buyer concessions, use the AU Mortgage Calculator.

Transfer tax estimates here are simplified averages. Always confirm with a conveyancer or solicitor in your jurisdiction before purchase. Use our savings calculator to plan your deposit and upfront costs.

Frequently asked questions

Mortgage repayments use the amortisation formula: M = P × r(1+r)^n / ((1+r)^n − 1). Here P is the loan amount (property price minus deposit), r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly repayments. Each payment covers two things: interest on the remaining balance, and a portion of the principal. In early years, most of each payment is interest — this shifts over time as the balance falls. Extra repayments attack the principal directly, which is why they save so much interest.

Deposit requirements vary by country. In Australia, most lenders require 10–20% — below 20% triggers Lenders Mortgage Insurance (LMI). In the US, conventional loans require 3–20%; below 20% attracts Private Mortgage Insurance (PMI). In the UK, 5–10% is typical for first home buyers. In NZ, the LVR rules generally require at least 20% for existing properties. A larger deposit means a smaller loan, lower monthly payments, lower interest costs over the life of the loan, and often a better interest rate. Use this calculator to compare the long-term savings of a larger deposit against keeping cash invested.

Every extra dollar reduces your principal balance, which lowers the interest charged next month. Because interest is always calculated on the remaining balance, principal reductions early in the loan term have the greatest compounding savings effect. On a $600,000 loan at 6.5% over 30 years, adding $500/month extra saves approximately $190,000 in interest and cuts 9 years off the term. Even $200/month extra saves around $85,000. Variable rate loans typically allow unlimited extra repayments; fixed rate loans often cap at $10,000–$20,000/year.

Transfer taxes (stamp duty, land transfer tax, buyer's stamp duty) are government charges on property purchases. They vary significantly by country and value: Australia: Stamp duty varies by state (6–7% on high-value homes in VIC/NSW). First home buyer concessions apply. UK: Stamp Duty Land Tax (SDLT) — 0% up to £250k, 5% on £250k–£925k, 10% on £925k–£1.5M. Canada: Land Transfer Tax varies by province (Ontario: ~1.5% average). Singapore: Buyer's Stamp Duty of 1–6% depending on price. NZ: No transfer tax. US: Transfer taxes vary by state (typically 0.5–2%).