“How much can I actually borrow?” It’s usually the very first question a client asks us at SG Luxury Condo, often before they’ve even picked a district. Fair enough, since there’s no point falling in love with a $2.5 million unit if the bank is only going to lend you enough for a $1.8 million one.

That’s exactly what our mortgage affordability calculator is built to answer. It’s not a rough guess, it’s based on the actual rules the Monetary Authority of Singapore requires every bank to follow. Once you understand how the calculation actually works, the number stops feeling like a mystery and starts feeling like a plan, which is exactly why SG Luxury Condo runs this calculation with clients before anything else.

TL;DR: Singapore’s mortgage affordability calculator works out your maximum home loan using MAS’s Total Debt Servicing Ratio (TDSR) framework, capping your total monthly debt at 55% of gross income, stress-tested at a 4% interest rate regardless of your actual mortgage rate. HDB flats and Executive Condominiums also face a separate 30% Mortgage Servicing Ratio (MSR) cap that private condos don’t. On top of TDSR, the bank will only lend up to 75% of the property’s value (Loan-to-Value ratio), so you’ll need at least 25% in cash or CPF for the rest. Run both numbers before you start viewing units, not after.

What a Mortgage Affordability Calculator Actually Calculates

A proper mortgage affordability calculator in Singapore isn’t estimating what you’d like to spend. It’s applying MAS’s TDSR framework to your actual income and debt to work out the maximum loan a bank is legally allowed to extend you. Two numbers come out the other end: your maximum loan tenure, and your maximum loan amount.

Here’s the thing most first-time buyers don’t realize. This number reflects your loan eligibility, not your full property budget. You’ll still need to factor in your downpayment, Buyer’s Stamp Duty, and possibly Additional Buyer’s Stamp Duty on top of whatever the bank approves.

The TDSR Framework, Explained Simply

Total Debt Servicing Ratio, or TDSR, caps how much of your gross monthly income can go toward all your debt obligations combined, home loan, car loan, personal loan, credit card debt, the lot. It applies to every residential property loan in Singapore, HDB and private alike.

The stress-test rate is the part that trips people up most. Even if your bank offers you a mortgage at 1.8%, MAS requires the calculation to assume you’re paying 4%, since mortgages run for decades and rates won’t stay low forever. This protects you from over-borrowing, but it also means the maximum loan amount a mortgage affordability calculator gives you will almost always be lower than what your actual monthly repayment might suggest you can afford.

MSR: The Extra Layer for HDB and EC Buyers

If you’re eyeing an HDB flat or an Executive Condominium bought directly from a developer, there’s a second, stricter cap to clear first: the Mortgage Servicing Ratio (MSR).

• MSR limits your monthly home loan repayment alone to 30% of gross monthly income
• It only applies to HDB flats and new ECs, private condos and resale ECs after privatisation are exempt
• For most HDB upgraders, MSR ends up being the binding constraint, not TDSR, since 30% is a tighter ceiling than 55%
• This is actually one reason some upgraders skip ECs entirely and go straight for a private condo, since MSR doesn’t apply and their full TDSR headroom becomes available instead

A Worked Example

Numbers make this easier to picture, so here’s a simplified example using a couple applying jointly.

• Combined gross monthly income: $16,000 ($10,000 fixed + $6,000 average variable, haircut to 70% = $4,200 counted)
• Existing debt: $500/month car loan
• TDSR cap: 55% x ($10,000 + $4,200) = $7,810/month
• Available for mortgage servicing: $7,810 − $500 = $7,310/month
• Maximum loan tenure: 35 years (assuming both applicants are under 30)
• Maximum loan amount at 4% stress rate: roughly $1.63 million

That $1.63 million is the bank’s ceiling, not your full property budget. Add in your 25% downpayment requirement under the Loan-to-Value rules, and this couple could realistically be looking at properties priced up to roughly $2.17 million, before accounting for stamp duties.

Don’t Forget the Loan-to-Value (LTV) Overlay

TDSR tells you your maximum loan based on income. LTV tells you your maximum loan based on the property’s value, and the bank always uses whichever number is lower.

This is exactly why running both a mortgage affordability calculator and an LTV check matters. Passing TDSR comfortably means nothing if you don’t have enough cash or CPF set aside to cover the LTV shortfall on a specific property.

Common Mistakes When Using an Affordability Calculator

We see these same mix-ups repeat themselves constantly, so SG Luxury Condo walks through each one with clients before they get too far into a decision.

• Assuming your actual mortgage rate applies. It doesn’t, MAS requires the 4% stress-test rate regardless of the promo rate your bank is quoting you today.
• Forgetting the variable income haircut. Bonuses and commissions only count at 70% of their value, not the full amount.
• Ignoring existing debt. Car loans, personal loans, and even credit card balances all reduce your available TDSR headroom.
• Mixing up TDSR and MSR. If you’re buying an HDB flat or new EC, MSR usually kicks in as the tighter limit, not TDSR.
• Not accounting for a second property loan. If you already have an outstanding home loan, your LTV drops sharply, from 75% down to 45% or even 35%.
• Treating the calculator’s ceiling as the target. The maximum loan figure is what the bank permits, not necessarily what fits comfortably into your monthly budget alongside everything else you’re paying for.

How to Use Our Mortgage Affordability Calculator

Getting an accurate result takes about two minutes, and it’s the same process SG Luxury Condo walks every new client through. Here’s what you’ll need on hand:

1. Your age, and your co-applicant’s age if buying jointly, since this determines your maximum loan tenure
2. Gross monthly fixed income for each applicant
3. Annual variable income, such as bonuses or commissions, for each applicant
4. Any existing monthly debt obligations, car loans, personal loans, or other credit facilities

Once you’ve entered these, the calculator applies the current MAS TDSR framework automatically and returns your weighted average age, combined gross monthly income, 55% TDSR limit, and your maximum loan amount and tenure. From there, our mortgage calculator can show you exactly what your monthly repayment would look like once you’ve settled on a specific purchase price.

Beyond the Loan: What Else Affects Your Total Budget

Passing TDSR and LTV is only part of the equation. Your total cash outlay also needs to cover Buyer’s Stamp Duty, and Additional Buyer’s Stamp Duty if it applies to your buyer profile. Our ABSD rates calculator can show you exactly how much extra you’d owe based on your citizenship status and how many properties you already own, which is worth checking before you finalise your maximum property budget.

A Word From SG Luxury Condo

We run this exact calculation with nearly every client before they start viewing units, because falling for a property you technically can’t get approved for wastes everyone’s time, including yours. A mortgage affordability calculator gives you the ceiling. What you actually want to spend, and what leaves you comfortable month to month, is usually a bit below that ceiling, not right up against it.

If your numbers are borderline, or you’re weighing a joint application, a second property purchase, or how decoupling might change your loan eligibility, SG Luxury Condo is happy to walk through the details with you. Our property consultation sessions cover exactly this kind of financing question, and our Singapore property investment advisors can help you plan a purchase that fits comfortably within your actual budget, not just your maximum eligibility. You’re also welcome to browse our full range of luxury condos for sale in Singapore once you know your numbers.