PMI Formula Explained
The PMI formula explained in plain English: the equation behind the PMI Calculator, its variables, and the assumptions it makes.
By Onias Derilus, Mortgage Capital · NMLS# 1859012 · Last Updated: June 2026
It estimates your monthly private mortgage insurance cost on a conventional loan. It also shows when you can expect to drop it as your equity grows.
The PMI Formula, Explained
Monthly PMI = (loan amount × annual PMI rate) / 12
PMI rates depend mostly on your down payment and credit score. A higher credit score and larger down payment both lower the rate. The premium is a percentage of the loan, charged monthly until you reach the equity threshold.
On conventional loans, PMI automatically terminates when the balance reaches 78% of the original value, and you can request removal at 80%. The calculator estimates how many payments that takes.
The formula is only the starting point. Open the pmi calculator to plug in your own numbers and see the result instantly. For a rate tied to your actual file, talk to a licensed broker before you decide.
Turn Your PMI Estimate Into a Real Pre-Approval
Get a personalized rate quote from a licensed Florida mortgage broker — no obligation. NMLS# 1859012.
Rates are illustrative only. APR and payments vary by credit score, loan amount, and market conditions. Subject to credit approval. Not a commitment to lend. NMLS# 1859012. Equal Housing Lender.