Combination Mortgage Calculator
Use this calculator to compare one mortgage with combination financing that consist of a first and second mortgage.
How the combination mortgage calculator works
It structures the purchase as an 80% first mortgage plus a smaller second mortgage to reach your down payment, then compares the combined payment against a single loan that requires PMI for the same down payment.
Worked example: with home price of $400,000, down payment of 10.00% and first mortgage rate of 6.50%, the combination (piggyback) mortgage calculator shows lower monthly payment of Piggyback (80-10-10).
- Piggyback payment
- $2,330.18
- Single loan + PMI
- $2,485.44
- First / second loans
- $320,000 / $40,000
- PMI avoided
- $210.00
The formula
Piggyback payment = payment on the 80% first + payment on the second. Single-loan payment = payment on the full loan + monthly PMI (if under 20% down).
Results are estimates for educational purposes and are not financial advice. Confirm exact figures with your lender, plan administrator or advisor.
Questions about the combination mortgage calculator
What is a piggyback or 80-10-10 mortgage?
A structure where a first mortgage covers 80%, a second covers 10%, and you put 10% down — avoiding PMI with less than 20% down by splitting the financing.
Is a piggyback cheaper than paying PMI?
Sometimes. It wins when the second mortgage’s cost is less than the PMI it replaces. The calculator compares both so you can see which is cheaper.
What are the downsides of a second mortgage?
It usually carries a higher rate and may be variable, and you have two loans to manage. If home values fall, the second loan can leave you underwater faster.
Is the Combination Mortgage Calculator free to use?
Yes. Every calculator on FinCalculators is completely free, with no sign-up, login or paywall. You can run as many scenarios as you like.