DTI calculator — NZ, Australia & US lending caps
Enter your income, existing debt and the loan you're thinking about. We'll show your debt-to-income ratio, whether it sits inside the regulator's cap, and how much more you could borrow before you breach it.
The number every property investor needs to know.
DTI — debt-to-income — is the ratio your bank cares about almost as much as LVR. In ratio markets like NZ and Australia, it's your total debt divided by gross annual income. In the US it's total monthly debt payments divided by gross monthly income.
New Zealand — RBNZ DTI rules
Since mid-2024 the RBNZ has set hard caps that banks must respect across most of their book: roughly 6× DTI for owner-occupiers and 7× for investors. There's a small "speed-limit" exemption window each quarter, but you can't plan around it. Stress-test serviceability is layered on top at around 8.5%.
Australia — APRA serviceability
APRA doesn't set a single hard DTI number, but it instructs banks to flag loans above 6× household DTI as high-risk. In practice, the major lenders won't serviceability-approve much past 6× without strong compensating factors. Stress-test buffer is typically 3% above the actual rate.
United States — 43% back-end DTI
Conventional Fannie Mae / Freddie Mac loans use a back-end DTI capped at 43% for qualified mortgages — that's all your monthly debt payments (proposed mortgage including taxes & insurance, plus existing car loans, student loans, credit-card minimums) divided by gross monthly income. Some non-QM lenders push further, but at a price.
What this calculator does
We pick the right model for your selected market and show three numbers: your DTI today (with the new loan included), the regulator's cap, and the maximum extra you could borrow before breaching it. The cap field is editable so you can model a stricter bank policy.
DTI calculator FAQ
What DTI ratio do banks actually use in New Zealand?
Since mid-2024 the Reserve Bank caps most owner-occupiers at 6× and investors at 7× total debt to gross annual income. Individual banks layer their own buffers on top, so the practical limit you'll see in pre-approval is often slightly lower. This calculator uses 7× as the default for NZ — change the cap to model a stricter bank.
Is Australia's DTI cap the same?
No. APRA expects banks to scrutinise loans above 6× household DTI as "high DTI", and most major lenders won't serviceability-approve much beyond that without strong compensating factors (large deposit, multiple income earners, low expenses). We default to 6× for AU.
Why is the US calculation different?
Conventional US lenders (Fannie Mae / Freddie Mac) use a payment-based DTI — your total monthly debt payments divided by gross monthly income — capped at roughly 43% for qualified mortgages. We approximate the new loan's monthly payment using your stress-test rate so the answer matches what the lender will see.
Does this replace a broker?
No. It's a fast first-pass check. A broker layers in real bank policies, your specific income mix, dependants, credit history and existing facilities — none of which a generic calculator can know. Use this to know whether the conversation is worth having before you book it.
Run the rest of the numbers
LVR calculator
Work out your LVR (or LTV in the US) and the deposit you need to clear investor and owner-occupied bands.
Cashflow calculator
Weekly and annual net cashflow on a rental, with rates, insurance, management, vacancy and interest baked in.
Stress-test calculator
See what your repayments look like at the bank's stress-test rate — the rate they actually use to approve you.
Rental yield calculator
Gross yield, net yield and cap rate for any rental — with weekly-rent input for NZ/AU and monthly for the US.
Stackhold runs every lending rule, in the same model as your tenants and cashflow.
DTI is one input. We build your full portfolio cockpit around it — for free.
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