Finance & Property · How to use
Mortgage Calculator
Follow the steps to enter your numbers and check the limits.
Updated 2026-10-25 · ThinkVault Tools
Get started in three steps
- 1
Step 1
Prepare your amounts, terms and applicable rates or prices.
- 2
Step 2
Open the tool, check the units and compare scenarios.
- 3
Step 3
Read the results and notes. Check official documents and sources before deciding.
Method and common questions
How is a mortgage payment calculated?
This tool uses the level-payment (annuity) method: every instalment is the same, but early payments are mostly interest. As the balance falls, a growing share goes to principal. Results include the monthly payment, total interest and total repayment, plus the first 24 rows of the amortisation schedule.
50% DSR and the rate-rise scenario are different things
DSR compares monthly debt payments with monthly income. This tool fixes 50% as an illustrative assumption and calculates reference income as current-rate payment ÷ 50%. It is not a statutory limit, a safe affordability level or loan eligibility in any jurisdiction. Lenders also consider other debts and individual terms.
Rate-rise scenarios are custom risk comparisons, not an official stress test or a lending decision. Check the latest rules in your location.
Example: a loan of 3,000,000 currency units
Assume 3,000,000 currency units at 3.5% for 25 years, or 300 payments: about 15,019 units a month. A 2% rise to 5.5% gives about 18,423 units. These are illustrative inputs, not local property prices or rate quotes. Use one currency throughout; changing the currency does not exchange the amounts.
Compare the effective rates of plans A and B
- Enter each plan’s actual annual borrowing rate. For variable rates, check the benchmark plus margin, caps and reset terms rather than entering the benchmark alone.
- Cash rebates, lock-in periods, mortgage-linked deposit accounts and insurance premiums are not included in the basic payment.
- Floating rates move with the market; test more than one rate scenario.
FAQ
- Is this a bank approval result?
- No. It is a budgeting estimate. Banks still assess income, credit history, other debts, property valuation and internal policy.
- Why is my bank’s figure slightly different?
- Banks may calculate by actual days, first payment date, rounding, fees and the rate effective date, so schedules can differ slightly.
- Why does 50% DSR not establish loan eligibility?
- 50% is a fixed comparison assumption in this tool, not a universal regulatory limit or lender approval. Check current local rules, lender terms and your other debts.
Method
Level monthly payments; after a teaser period, re-amortise the balance at the effective rate. Fixed illustrative reference income = current-rate payment ÷ 50%. The 50% assumption is not a jurisdiction’s approval rule; taxes, fees and eligibility are not applied automatically.
OpenStax: loan amortization mathematics (English)Last checked: 2026-10-24
Before you begin
Tax, lending, holiday and protection rules vary by place and date. Check current local rules and provider terms. Results are estimates.