How Mortgage Payments Are Calculated: PITI and PMI Explained
Quick Answer: How Mortgage Payments Are Calculated
Your monthly mortgage payment consists of up to five components, often abbreviated as PITI + PMI: Principal, Interest, Taxes (property tax), Insurance (homeowner's insurance), and optionally PMI (Private Mortgage Insurance, required if your down payment is less than 20%). Use the FinanceFlows Mortgage Calculator to calculate your complete monthly payment across all components for any loan scenario. Also see: Why Are Mortgage Rates Rising in 2026?
The Mortgage Amortization Formula
The P+I (principal + interest) portion of your mortgage is calculated using the standard amortization formula:
Monthly P+I = P × [r(1+r)^n] ÷ [(1+r)^n − 1]
Where:
P = Loan principal (purchase price minus down payment)
r = Monthly interest rate (annual rate ÷ 12)
n = Total number of payments (loan term in years × 12)
Example: $400,000 loan at 6.75% for 30 years:
- Monthly rate (r) = 6.75% ÷ 12 = 0.5625% = 0.005625
- n = 30 × 12 = 360 payments
- Monthly P+I = $2,594
Breaking Down the Full Monthly Payment (PITI + PMI)
| Component | What It Is | Example (on $500K home) |
|---|---|---|
| Principal (P) | The portion of your payment that reduces your loan balance | ~$645/month (year 1) |
| Interest (I) | The cost of borrowing — the lender's profit | ~$1,949/month (year 1) |
| Property Taxes (T) | Annual property taxes ÷ 12, collected by lender in escrow | ~$500/month (varies by location) |
| Homeowner's Insurance (I) | Annual premium ÷ 12, collected in escrow | ~$150/month |
| PMI (if <20% down) | Private Mortgage Insurance — protects lender if you default | ~$130–$250/month (on $400K loan) |
| Total Monthly Payment | Everything your lender collects each month | ~$3,374–$3,494/month |
How Amortization Works: Why Early Payments Are Mostly Interest
In the early years of a mortgage, the vast majority of your payment goes to interest, not principal. This is how amortization works — it's not a trick, it's math:
| Year | Principal Paid | Interest Paid | Remaining Balance |
|---|---|---|---|
| Year 1 | $7,759 | $23,372 | $392,241 |
| Year 5 | $9,112 | $22,019 | $362,400 |
| Year 15 | $13,824 | $17,307 | $274,700 |
| Year 25 | $20,983 | $10,148 | $127,800 |
(Based on $400,000 loan at 6.75%, 30-year fixed)
Private Mortgage Insurance (PMI): When You Need It and How to Remove It
PMI is required when your down payment is less than 20% of the home's purchase price. It protects the lender (not you) against default.
- PMI cost: Typically 0.5%–1.5% of the loan amount per year ($2,000–$6,000/year on a $400K loan)
- How to remove it: PMI must be cancelled when your loan-to-value (LTV) ratio reaches 80% (either through payments or home appreciation). By law (Homeowners Protection Act), lenders must automatically cancel PMI at 78% LTV
- Accelerating removal: Extra principal payments speed up the timeline to 80% LTV and PMI cancellation
15-Year vs. 30-Year Mortgage: The Real Cost Difference
| Feature | 15-Year Mortgage | 30-Year Mortgage |
|---|---|---|
| Monthly P+I (on $400K) | $3,433 (at 6.25%) | $2,594 (at 6.75%) |
| Total Interest Over Life | $218,000 | $534,000 |
| Interest Savings with 15-Year | $316,000 saved in interest — at the cost of $839/month higher payment | |
Compare your own scenarios with the Mortgage Calculator and the Loan Comparison Calculator side-by-side.
🏠 Calculate Your Complete Mortgage Payment
Enter your home price, down payment, interest rate, and taxes/insurance to see your full PITI payment, total cost of the loan, and year-by-year amortization schedule.
Use the Mortgage Calculator →Frequently Asked Questions: How mortgage payments work
What is how mortgage payments work and why does it matter?
How mortgage payments work provides crucial financial direction for investors and households. Understanding how mortgage payments work helps you make informed allocation choices, reduce unnecessary fees, and optimize your overall returns.
How can you apply how mortgage payments work in your financial strategy?
To implement how mortgage payments work successfully, start by assessing your current risk profile and timeline. Consistently monitoring how mortgage payments work ensures your portfolio stays aligned with long-term goals.
What are common pitfalls to avoid with how mortgage payments work?
The most common mistake when evaluating how mortgage payments work is reacting to short-term market noise. Focus on verifiable data, compound growth, and proven principles when making decisions based on how mortgage payments work.