Second home mortgage calculators
Five tools that work entirely from numbers you enter. They recommend nothing, store nothing and send nothing anywhere.
Written by Bryan Piccolomini, NMLS #228509, a mortgage loan originator with Residential Mortgage, LLC (NMLS #167729), a wholly owned subsidiary of Northrim Bank. Loans are originated through Residential Mortgage, LLC.
Down payment and amount financed
The starting arithmetic on any purchase. Pick a price and a scenario, and see what has to come out of pocket and what gets financed.
Down payment and loan amount
Enter a price you are considering and pick a scenario to model. These are simply common scenarios buyers ask about, not a recommendation or a requirement for your file.
Purchase price minus your chosen down payment. It does not include closing costs, taxes, insurance or reserves. Estimate for planning only. Not an offer, an approval, or a quote.
What actually sets the down payment on your file is the loan program and the rest of your profile rather than a scenario in a dropdown. For conforming loans, Fannie Mae's Eligibility Matrix, August 2026 edition, lists 90% as the maximum loan-to-value on a one-unit second home purchase, which works out to a 10% minimum down payment. Jumbo, non-QM and portfolio lending each set their own terms.
Read next: Down payment on a second home · What loan options exist · Closing costs
Debt-to-income with both housing payments
The number that decides more second home files than anything else, because the mortgage you already carry counts in full while the new loan is reviewed.
Your debt-to-income ratio
This is the same arithmetic a lender does: everything you pay monthly, divided by what you earn monthly. There is no single cutoff that applies to everyone, and this is not a decision on your file. It tells you where you are starting from.
Include the mortgage on your current home, car payments, student loans, and minimum credit card payments. Lenders weigh this alongside the rest of your file rather than on its own. Estimate for planning only. Not an offer, an approval, or a quote.
There is no single national cutoff to compare your result against. The CFPB removed the General Qualified Mortgage 43 percent limit in its December 2020 final rule and replaced it with price-based thresholds; a later rule moved the mandatory compliance date to October 1, 2022. The ratio still matters; it is simply not governed by that one number any more.
Read next: Debt to income for a second home · Self-employed buyers
Equity available in the home you already own
Most second home purchases are funded at least partly from the first house. This shows what is theoretically reachable at a loan-to-value you choose.
How much equity you have to work with
Enter what your current home is worth and what you still owe. Pick a loan-to-value to model; lenders differ, and the one that applies to you depends on the program and your file.
Total equity is your home’s value minus what you owe. The second figure is what would remain accessible at the loan-to-value you picked, before costs. Whether tapping it makes sense against your existing rate is the actual conversation. Estimate for planning only. Not an offer, an approval, or a quote.
The 80% default is not arbitrary. Fannie Mae's Eligibility Matrix, August 2026 edition, lists 80% as the maximum loan-to-value on a one-unit principal residence cash-out refinance, which is the route most second home buyers ask about. Whether it is worth doing against the rate you already hold is the actual conversation.
Read next: Using your equity to buy a second home · Refinancing a second home
Second home or investment property? A quick check
The answer decides which loan you are shopping for, so it is worth settling before you compare anything else. Seven yes-or-no questions, based on Fannie Mae's definition of a second home.
How will you actually use the home?
Answer for how you really plan to use it, not how you hope it gets classified. Nothing you choose here is stored or sent.
Answer the questions above to see how your plans line up.
A plain-English reading of Fannie Mae Selling Guide B2-1.1-01, the definition most conventional second home loans follow. Jumbo, portfolio and non-QM lenders can set their own rules. It is a planning aid, not a determination, an offer or an approval.
An investment property is not a worse loan, it is a different one. The Fannie Mae Eligibility Matrix lists a lower maximum loan-to-value for a one-unit investment purchase than for a second home, and reserve expectations are typically higher. Settling the classification before an offer avoids finding out at appraisal.
Source: Fannie Mae Selling Guide B2-1.1-01, Occupancy Types. Read next: Second home vs. investment property · Occupancy requirements
The true monthly cost of a second home
A lender looks at part of what a second home costs. You pay all of it. This splits the two so the number you plan around is the real one.
What the lender counts, and what it doesn't
Every figure comes from you. Use a payment estimate from a lender quote if you have one. Nothing is stored or sent.
What a lender counts toward debt-to-income
From a lender quote or your own estimate
Annual tax divided by 12. Second homes rarely get a homestead break
Homeowners, plus flood or wind if the area needs it
Leave blank if none
What you pay that a lender never sees
Power, water, internet, trash, kept on all year
Your own estimate; older and coastal homes run higher
What it costs to have someone look after it while you are away
Fuel or flights, averaged across the year
The lender figure is the housing expense that goes into a debt-to-income calculation; carry it into the debt-to-income calculator above. The second figure never shows up in underwriting, which is why it is the one that surprises people. Planning estimate only. Not an offer, an approval, or a quote.
Two things tend to move the lender number most on a second home: insurance in coastal and wildfire areas, where flood or wind coverage is often a separate policy, and property tax, because the reduced rates many states give a primary residence usually do not apply. Both are worth pricing with real quotes before an offer rather than after.
From Bryan’s desk. Insurance is the cost Bryan sees second home buyers overlook most, and out-of-state buyers are the most surprised by it.
On new construction, add the things a builder does not include. Landscaping and window coverings are the two Bryan names, and covering a house with around 20 windows runs into the thousands on its own.
Bryan Piccolomini, NMLS #228509, in an interview for this site, October 2026.
Read next: Debt to income for a second home · Closing costs · State-by-state notes
What a number does not tell you
Occupancy classification, the property type, and how your income is documented decide as much as the arithmetic does. These three guides cover the parts a calculator cannot.
About these calculators
Is this a second home mortgage calculator I can rely on?
It is a planning tool. Each calculator works only from the numbers you type in, it stores nothing and it sends nothing anywhere. None of the figures it shows is an offer, an approval, or a quote, and none of them takes account of the rest of your file.
Why does the down payment calculator not show a monthly payment?
A payment figure would need an interest rate, and no rate can be known before a lender has reviewed your file and the property. Publishing one would be inventing a number. The calculator stops at down payment and amount financed, which are arithmetic rather than estimates.
What should I put in the debt-to-income calculator?
Gross monthly income before tax, then everything you pay monthly that appears on your credit report, including the mortgage on the home you already own, car payments, student loans and minimum credit card payments. Add your estimate of the new second home payment in the third field.
Do these calculators work for a vacation home?
Yes. A cabin, a beach house or a resort condominium bought for your own part-year use is the same occupancy classification as any other second home, so the same arithmetic applies.
Put your number in front of someone
A figure from a calculator is a starting point. What it means for your file takes a short conversation.