If you read PMI Explained, you know an 80-10-10 piggyback loan is a real way to skip PMI without a full 20% down payment, and that it isn’t automatically the cheaper choice. The second loan carries its own rate, and whether that ends up costing you more or less than PMI depends on numbers that are genuinely hard to eyeball: your credit-based PMI rate, the second loan’s rate and term, and how long you’re actually planning to keep the house before selling or refinancing.

Short version: Enter your loan numbers and how long you plan to stay, and this shows which path costs less in total interest and PMI, plus exactly when the two paths would cross over if your inputs change.

Here's what matters most for reading your results honestly. PMI is temporary, it cancels automatically once your loan balance hits 78% of the home's original value, but you keep paying interest on the extra principal it let you borrow for the entire loan term. The piggyback's second loan carries a higher rate, but only for its own term, once it's paid off, that extra cost disappears completely. Which one wins depends on how those two clocks line up against how long you're actually staying. Run your own numbers below, not the defaults, your credit tier and the actual second-loan quote you can get both move this more than people expect.

One thing to understand before you trust the verdict number: it's not only comparing your monthly payment, it's comparing what that payment actually buys you. The piggyback path often costs a bit more per month, but a bigger share of that extra money goes toward equity - paying down principal instead of interest, since the second loan typically pays off faster (15 years is a common term, versus 30 for a standard mortgage), and principal paid is equity you keep, not money that's gone. So the tool only counts interest and PMI as "cost," the parts that are genuinely gone for good, and treats principal as a wash since it builds equity no matter which loan it went through. A path that costs more cash out of pocket each month can still come out ahead once that extra equity gets counted. The results include an "extra cash paid" and "extra equity built" row for exactly this reason, so you can check the reconciliation yourself instead of taking the verdict on faith.

One thing this tool intentionally doesn't try to model: the new 2026 PMI tax deduction and the tax treatment of the second loan's interest. Both depend on your income and whether you itemize, covered in full in PMI Explained, and trying to simulate someone's specific tax situation inside a mortgage calculator adds complexity without adding real accuracy. This compares pre-tax cost only, your actual after-tax numbers could shift slightly in either direction.