Second home mortgage calculators
Three 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
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.