Combined Loan-to-Value Calculator

Combined LTV is what second-mortgage lenders actually care about. A 200,000 first mortgage plus a 40,000 home equity line on a 300,000 property = 80% combined LTV. Above 80-85% combined LTV, most lenders stop offering new second loans. Knowing your combined LTV is the first step before shopping for home equity financing.

Run it with sensible defaults

Using first mortgage balance of 200,000, second loan / heloc balance of 40,000, property value of 300,000, the calculation works out to 80.00%. The defaults are meant as a starting point, not a recommendation.

The levers in this calculation

The inputs — First Mortgage Balance, Second Loan / HELOC Balance, and Property Value — do not pull with equal force. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

How the math works

Combined loan balances divided by property value. Standard second-mortgage underwriting metric.

Stress-testing the plan

Run the calculation at your current rate, then run it again at a rate 2–3 percentage points higher. That's roughly what a product reset could bring at renewal, and it's a useful check on whether you can afford the mortgage in a higher-rate world, not just today's.

What this doesn't capture

The figure excludes arrangement fees, valuation costs, legal fees, insurance, and any early-repayment charges — those can add several thousand to the headline cost. Rate changes at renewal for fixed-term deals will shift the picture further. Use this for the core interest/principal math and add the other costs on top.

Worked example

A property owner has a first mortgage balance of 250,000 on a home valued at 400,000. They also carry a home equity line of credit with a current balance of 60,000. The combined LTV calculates as:

(250,000 + 60,000) ÷ 400,000 = 77.5%

This combined LTV of 77.5% sits below the typical lending ceiling for new second-mortgage products. If the property value falls to 380,000 while both loan balances remain unchanged, the combined LTV rises to 81.6%, potentially affecting availability of additional credit or terms offered by lenders.

When this metric matters

• Assessing eligibility for a new second loan or home equity product
• Understanding how property value changes affect borrowing capacity
• Comparing multiple scenarios before committing to additional secured debt
• Monitoring risk exposure when property markets fluctuate
• Planning debt consolidation or refinance structures across multiple loans

What the result shows

Combined LTV expresses, as a percentage, how much of your property's value is committed to repay all secured debt. A result of 75% means that three-quarters of the property serves as collateral for mortgages and other loans. It does not account for equity cushion (the gap between combined debt and property value that protects a lender in default scenarios), nor does it address individual loan terms, interest rates, or monthly payment capacity.

What the result does not capture

Combined LTV ignores the structure and pricing of each loan separately. Two properties with identical 75% combined LTV may carry very different risk profiles if one has a first mortgage at a fixed rate and a second loan at a floating rate, while the other has the opposite. The metric also omits property-specific factors such as condition, location, and market liquidity, all of which lenders weigh during underwriting.

Educational illustration

This calculator models combined loan-to-value for illustration purposes. The result shows a mathematical relationship between total secured debt and property value as you input them. It does not account for individual lender policies, eligibility criteria, or real-world application outcomes. Use it to understand the concept and explore scenarios, then discuss actual numbers with lenders or financial professionals.