Singapore's mortgage calculator shows your monthly repayment and total interest in seconds. Enter your loan amount (up to 75% LTV for a first private bank loan), your interest rate, and your loan tenure (capped at 30 years for private property or 25 for HDB). The tool does the amortisation math so you can compare scenarios before committing to a home loan (as of 2026-06).
A home loan is likely the largest financial commitment you will ever make, and the monthly repayment figure is the number that shapes your budget for decades. Yet many buyers quote a developer's indicative instalment without verifying it against their own inputs — loan quantum, the rate their bank actually offered, and a tenure that fits their age. The ShiokNest mortgage calculator lets you plug in your own numbers and see exactly what you owe each month, how much of each payment goes to interest versus principal, and what you will have paid in total by the final instalment. This guide explains every input, walks through the amortisation mechanics, and shows you how to run the scenarios that matter — including stress-testing your affordability before you sign an option to purchase.
What the inputs mean and where the limits come from
Three numbers drive every mortgage calculation: the loan amount, the interest rate, and the loan tenure.
Loan amount and LTV. For a first private property purchase with a bank loan, the Monetary Authority of Singapore caps the Loan-to-Value (LTV) ratio at 75% of the lower of the purchase price or the property's market valuation — meaning you must fund the remaining 25% from cash and CPF. The cap drops to 45% if you already have one outstanding loan, and to 35% if you have two or more. For HDB flats, the HDB concessionary loan allows up to 80% LTV under its own eligibility rules — see HDB's loan eligibility guide for full conditions — while a bank loan on an HDB flat follows the same 75% private bank cap. These limits are set by MAS and updated periodically; always check MAS's official LTV explainer for the current figures before planning your downpayment.
Interest rate — fixed or SORA-based floating. Singapore banks offer two main rate types. Fixed rates lock your repayment for an initial period — typically two to three years — after which the loan re-prices to the bank's prevailing board rate or a floating benchmark. Floating rates are pegged to the Singapore Overnight Rate Average (SORA), published daily by MAS. A SORA-pegged loan means your monthly payment moves with short-term market rates, which can fall or rise. For HDB buyers using the HDB loan, the concessionary rate is set at 0.1% above the prevailing CPF Ordinary Account interest rate — currently 2.6%, making the HDB loan rate 2.6% (as of 2026-06). See MAS's home loan guide and CPF interest rates for current benchmarks.
Tenure limits. MAS rules cap private bank loan tenures at 30 years for private property and 25 years for HDB flats. There is a second constraint: if the loan tenure extends beyond the borrower's 65th birthday, the LTV limit is reduced. For example, a 35-year-old buyer on a 30-year tenure reaches 65 exactly at loan maturity — that is on the boundary. A 40-year-old taking a 30-year loan would run to 70, triggering the reduced LTV. The practical rule: tenure should generally not push loan maturity past age 65, or you accept a lower maximum loan quantum. Many buyers set their tenure to exactly 65 minus their current age to maximise the LTV while keeping repayments manageable.
- A 1% rise in interest rates on a $1M loan adds roughly $500/month to your payment.
- Total interest paid often exceeds 40-60% of the original loan amount over 25-30 years.
- Compare your monthly mortgage payment against expected rental income to gauge cash flow.
- Shorter loan tenures cost more per month but save significantly on total interest.
What will your monthly mortgage payment actually be? And can you afford it? These are the two most important questions for any Singapore property buyer, and most people rely on back-of-the-envelope guesses or the bank's quoted figure. This calculator gives you the exact answer — plus shows you the total interest you will pay over the life of your loan, which is often a jaw-dropping number.
Whether you are buying your first home or refinancing an existing mortgage, understanding your monthly obligation down to the dollar is non-negotiable.
What This Calculator Does
Find out exactly what your monthly mortgage payment will be and how much total interest you will pay. Compare mortgage costs against rental income to see if your investment property generates positive cash flow. Essential for every Singapore property buyer.
You can find this calculator in the Calculators tab on ShiokNest. It updates results instantly as you adjust inputs — no waiting, no page reloads.
Why This Matters
Your mortgage payment is the number you live with every single month for 20-30 years. Getting it wrong by even a few hundred dollars can mean the difference between financial comfort and stress. This calculator matters because:
- Total interest on a $1.125M loan at 3.5% over 25 years exceeds $500K — half the loan amount again
- A 1% rate increase raises your monthly payment by roughly $500-$600 on a typical loan
- Understanding cash flow (rent vs mortgage) determines whether your investment property is self-funding or a monthly drain
What You Will Discover
After running this calculator with your personal numbers, you will know:
- Your exact monthly mortgage payment, down to the dollar
- Total interest paid over the full loan tenure — often a shocking number
- Monthly cash flow when comparing mortgage against rental income
- How different rates and tenures change your financial picture
Key Inputs Explained
Here are the inputs you will configure, along with their default values. Each default is calibrated to a realistic Singapore condo scenario so you can explore results immediately.
| Field | Description | Default Value |
|---|---|---|
| Purchase Price | The total property price before additional costs. | $1,500,000 |
| Down Payment (%) | Your cash/CPF contribution as % of price. | 25.0% |
| Interest Rate (%) | Annual loan interest rate. | 3.5% |
| Loan Tenure (Years) | Duration of the mortgage loan. | 25 years |
| Monthly Rent | Expected monthly rental income or rent you would pay. | $3,800 |
Step-by-Step Guide
- 🏠 Navigate to Calculators — Click the "Calculators" tab in the ShiokNest navigation bar. All 26 calculators are grouped by purpose for easy access.
- 🔍 Select the calculator — Choose "How to Use the Mortgage Calculator" from the calculator list. You will see default values already loaded so you can explore immediately.
- ✏️ Enter your values — Replace the defaults with your own numbers. The key fields are:
- Purchase Price — The total property price before additional costs.
- Down Payment (%) — Your cash/CPF contribution as % of price.
- Interest Rate (%) — Annual loan interest rate.
- Loan Tenure (Years) — Duration of the mortgage loan.
- Monthly Rent — Expected monthly rental income or rent you would pay.
- 📊 Review the results — The calculator updates instantly as you change any input. You will instantly see your monthly payment, total interest over the full tenure, and cash flow comparison if you entered a rental figure.
- 🔄 Run what-if scenarios — This is where the real power lies. Change one variable at a time to see its impact. For example, try increasing the interest rate by 1% or extending your holding period by 5 years. Note how the results shift.
- 💾 Compare and decide — Run 2-3 different scenarios and note the results. This gives you a range of outcomes to base your decision on, rather than relying on a single projection.
Worked Example
Meet James and Mei, a dual-income couple buying a $1,500,000 condo. They put down 25% ($375,000) and borrow $1,125,000 at 3.5% over 25 years. They also plan to rent out a room for $3,800/month to offset costs.
The interest reality check: On a $1,125,000 loan, James and Mei will pay a total of $564,605 in interest alone — that is 50% of the loan amount. This is money that does not build equity. Shortening the tenure or making extra repayments can dramatically reduce this number.
Cash flow check: With rent of $3,800/month against a mortgage of $5,632/month, they are short by $1,832/month — they need to cover this gap from their salaries.
Real-World Scenarios to Try
Here are some realistic scenarios you can plug into the calculator right now. Each one reflects a common situation Singapore property buyers face.
| Scenario | Settings to Try | What You Will Learn |
|---|---|---|
| Aggressive paydown | 25% down, 3.5% rate, 20-year tenure | How a shorter tenure saves massive interest despite higher monthly payments |
| Maximum leverage | 25% down, 3.5% rate, 30-year tenure | The lowest possible monthly payment — and its true long-term cost in interest |
| Rate shock test | 25% down, 5.0% rate, 25-year tenure | Whether you can still afford payments if rates rise significantly |
Expert Tips and Common Pitfalls
💡 Pro Tips
- Use realistic assumptions — Singapore condo appreciation has historically averaged 2-4% per year. Avoid overly optimistic projections. When in doubt, use 3% as a baseline.
- Stress-test at 5% — The current rate environment may be low, but rates have been 4-5% in the past. Test at 5% to ensure you can still sleep at night.
- Consider shorter tenure — A 20-year loan instead of 30-year costs more per month but saves a massive amount in total interest. Run both to see the difference.
- Check TDSR first — Even if you can find the cash, banks must comply with TDSR limits. Use our TDSR calculator before assuming your loan will be approved.
⚠️ Common Pitfalls
- Only looking at monthly payment — A 30-year loan has a lower monthly payment than a 20-year loan, but you pay vastly more in total interest.
- Forgetting about rate resets — Fixed-rate periods end. When your rate resets to MAS SORASORA + spread, the monthly payment can jump significantly.
🤔 What-If Scenarios to Explore
Get the most value from this calculator by testing these scenarios:
- What if you increase your down payment from 25% to 35%? How much interest do you save?
- What if you choose a 20-year tenure instead of 25? Compare the total interest paid.
- What if rates rise from 3.5% to 5% after your fixed period ends?
- Run at least 3 scenarios — best case, base case, and worst case — to understand the full range of outcomes.
Related Calculators
Your property journey involves many interconnected decisions. These calculators work hand-in-hand with this one:
- How to Check TDSR and MSR Affordability
- How to Read the Borrowing Sensitivity Heatmap
- How to Compare Mortgage Loan Packages
Ready to Crunch Your Numbers?
Enter your loan amount, interest rate, and tenure to see your exact monthly payment and total interest. Then stress-test with a higher rate to make sure you can handle the worst case.
Official Sources
This how-to guide is auto-generated using ShiokNest's calculator defaults. All worked examples use default values — adjust inputs to match your personal scenario for accurate results.
Common Mistakes to Avoid
Always calculate total interest over your expected holding period, including the floating rate phase. Use the Loan Comparison calculator to model multi-phase rates.
A 30-year loan at 3.5% costs ~80% more in total interest than a 20-year loan. Balance affordability with total cost by comparing different tenures in the calculator.
Stress-test your mortgage at rates 1-2% higher than current rates. Use the Borrowing Sensitivity Heatmap to visualise the impact of rate changes across multiple scenarios.
Most fixed-rate packages include a 1.5% clawback penalty during the lock-in period. If you plan to sell or refinance within 2-3 years, factor this cost into your calculations.
How amortisation works — and why it matters for your total cost
Every monthly repayment on a standard annuity (level-payment) mortgage is split between interest on the outstanding balance and principal reduction. The formula for the monthly payment M is:
M = P × [r(1+r)n] / [(1+r)n − 1]
where P is the initial loan principal, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments. The result is a fixed monthly amount — but what sits beneath it shifts dramatically over time. In month one, almost all of M is interest (because the outstanding balance is close to P); by the final month, almost all of it is principal. This front-loading of interest is why early repayment or lump-sum prepayments have a disproportionately large effect on total interest paid.
Worked example (as of 2026-06). Suppose you borrow S$750,000 at a fixed 3.5% per annum over 25 years (300 months). The monthly rate is 3.5% ÷ 12 = 0.2917%. Applying the formula: M ≈ S$3,752. Over 300 months, total payments = S$3,752 × 300 = S$1,125,600. Total interest = S$1,125,600 − S$750,000 = S$375,600 — roughly 50% of the original loan amount paid in interest alone.
Now extend the tenure to 30 years (360 months) at the same rate. Monthly payment drops to approximately S$3,367 — saving S$385 per month. But total interest jumps to roughly S$461,120 — nearly S$86,000 more over the life of the loan. The lower monthly payment is real and valuable if cash flow is tight, but the true cost is higher. Run both scenarios side by side in the mortgage calculator to see the exact numbers for your loan.
Rate sensitivity. A 1% increase in interest rate on a S$750,000 loan over 25 years raises the monthly payment by roughly S$390 and total interest by approximately S$117,000. This is why MAS requires banks to stress-test your repayment capacity at a higher rate. Under the Total Debt Servicing Ratio (TDSR) framework, banks must calculate your monthly obligations using a stressed interest rate — currently MAS guidance sets the stress rate floor at 4.0% per annum for property loans. Your total monthly debt obligations (including the stressed mortgage payment) must not exceed 55% of your gross monthly income. Read the MAS TDSR explainer for the full rules. This means the maximum loan a bank will grant you is determined by your income, not just by the LTV cap — sometimes the income constraint binds tighter than the LTV limit.
To discover how much you can borrow before running the mortgage calculator, use the affordability calculator, which applies the TDSR 55% ceiling to your income and existing commitments. Once you have an estimated loan quantum, move to the mortgage calculator to see the repayment schedule, then visit the refinancing calculator to model whether switching to a lower rate mid-loan saves money after accounting for legal and valuation fees.
District and property comparisons can also affect your decision on loan quantum — viewing side-by-side property comparisons or checking rental yield maps helps you ground your borrowing decision in actual market data for the area you are targeting.
Step by step: using the mortgage calculator
- Open the calculator. Navigate to ShiokNest Mortgage Calculator. The page loads with default illustrative values — do not rely on these; replace every input with your own numbers before reading the output.
- Enter the loan amount. Input the actual loan you plan to take, not the purchase price. For a S$1,000,000 private property with a 75% LTV first bank loan, the maximum loan is S$750,000. If you are making a larger downpayment, enter the smaller loan amount to see its effect on monthly repayments and total interest.
- Set the interest rate. Use the rate stated in your bank's Letter of Offer for the fixed period (e.g., 2.8% fixed for two years). If you are modelling a SORA-pegged loan, use the current SORA plus the bank's spread — check your indicative term sheet. For a conservative scenario, add 0.5%–1.0% to the offered rate to approximate what repayments look like if rates rise. This mirrors the MAS-mandated stress-test logic banks apply under the TDSR framework.
- Choose the tenure. Start with the longest permissible tenure for your property type (30 years for private, 25 for HDB) to see the minimum monthly payment. Then shorten the tenure by five-year increments and observe how total interest falls with each reduction. Balance the monthly saving from a longer tenure against the extra interest cost shown in the summary.
- Check the age constraint. If extending the tenure would push loan maturity past your 65th birthday, note that MAS rules reduce the maximum LTV — you may need a larger cash downpayment. Recalculate with the lower loan amount if this applies.
- Read the amortisation summary. The calculator displays: monthly payment, total amount paid, and total interest. Use these three figures — not just the monthly — to compare loan packages. Two packages with similar monthly payments can differ by tens of thousands in total interest if their tenures differ.
- Run a rate shock scenario. Increase the interest rate by 1.5 percentage points and re-calculate. If the resulting monthly payment exceeds 30%–35% of your take-home pay, the loan may be stretched. Cross-check against your full debt picture in the affordability calculator to verify TDSR headroom.
- Compare refinancing economics. After you have your base repayment schedule, visit the refinancing calculator and model what happens if you switch to a lower rate two or three years into the loan. Account for the one-time legal fee (typically S$2,500–S$3,000) and valuation fee (S$500–S$800). A genuine rate saving of 0.5% or more usually clears the breakeven point within 12–18 months of switching.
- Save or share your scenario. Copy the URL with your parameters or screenshot the summary. When speaking to a bank officer or mortgage broker, sharing your computed monthly and total interest lets you ask pointed questions about how their package compares — rather than accepting a single headline rate.