Second Mortgage Payment Calculator
Estimate the monthly payment, total interest and combined loan-to-value of a second mortgage or home-equity loan behind your first lien.
How it works
Payment = P × i ÷ (1 − (1 + i)⁻ⁿ), i = rate ÷ 12, n = term × 12 · CLTV = (first balance + second) ÷ home value
A second mortgage — a home-equity loan sitting behind your first lien — is a fully amortizing loan, so it uses the same payment formula as any mortgage. Rates run higher than a first mortgage because the second lender is repaid only after the first in a foreclosure, so it carries more risk. Lenders also watch combined loan-to-value: the first balance plus the new second divided by the home value, usually capped around 80–90%.
Worked example
A $50,000 second mortgage at 9% over 15 years is about $507/mo. Over 180 payments you pay roughly $91,300, of which $41,300 is interest. With a $250,000 first balance on a $400,000 home, CLTV is (250,000 + 50,000) ÷ 400,000 = 75%.
Frequently asked questions
Why is a second mortgage rate higher than my first?
In a default the first-lien lender is paid in full before the second lender sees a dollar. That subordinate position is riskier, so second mortgages and home-equity loans price several points above comparable first mortgages.
What is CLTV and why does it matter?
Combined loan-to-value adds every mortgage against the home and divides by its value. Most lenders cap CLTV around 80–90%; a high CLTV limits how much you can borrow on the second and can raise the rate.
How is a second mortgage different from a HELOC?
A second mortgage (home-equity loan) is a lump sum at a fixed rate with a set payment. A HELOC is a revolving line you draw from as needed, usually at a variable rate — see the HELOC draw & repay calculator.
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Educational estimate, not financial, tax or lending advice. Confirm figures with your lender, agent or a qualified professional.