Home Mortgages: Full P&I, PMI, Affordability & Amortization

📊 The US Mortgage Market by the Numbers

The US mortgage market is $12.5 trillion — the largest consumer debt category. A $350K mortgage at 6.5% for 30 years costs $447K in interest — 128% of the borrowed amount. The first 10 years of payments are mostly interest (72% in year 1!). Making one extra payment per year on a 30-year mortgage cuts the term by 4.5 years. Mortgage rates hit a 23-year high of 7.79% in October 2023.

Sources: Federal Reserve, Freddie Mac, CFPB, Mortgage Bankers Association

📐 Mortgage Payment Formula Explained

The standard mortgage payment formula is M = P × [r(1+r)^n] / [(1+r)^n - 1], where M = monthly payment, P = principal loan amount, r = monthly interest rate (annual ÷ 12), and n = total number of payments (years × 12).

🔒 Fixed vs Adjustable Rate Mortgages

Fixed-rate mortgages lock in your rate for the full term — predictable payments but often higher initial rates. ARMs (e.g., 5/1 ARM) offer lower initial rates for the first 5 years, then adjust annually based on market indices. ARMs suit buyers who plan to sell or refinance within 5–7 years. If rates rise, ARM payments can increase significantly.

📉 Mortgage Amortization

Amortization is the process of paying off a loan through regular payments. Early payments go mostly to interest (e.g., 72% in year 1 on a 30-year loan); later payments go mostly to principal. The balance declines over time until the loan is paid off. Extra principal payments reduce total interest and shorten the term — even small amounts add up.

Use the amortization chart above to visualize how your balance, principal paid, and interest paid change over the life of the loan.

💰 Mortgage Points

Mortgage points (discount points) are upfront fees paid to lower your interest rate. One point typically costs 1% of the loan amount and reduces the rate by approximately 0.25%. Calculate breakeven: point cost ÷ monthly savings. If you stay in the home past breakeven, points save money. Example: $3,500 for 1 point on $350K loan, saving $48/month = breakeven in ~73 months (6 years).

🏦 Escrow Accounts

An escrow account holds funds for property taxes and homeowners insurance. The lender collects 1/12 of annual costs each month and pays bills when due. Escrow ensures you don't face large lump-sum bills and protects the lender's collateral. Lenders often require escrow when LTV exceeds 80%.

✅ Pre-Qualification vs Pre-Approval

Pre-qualification is an informal estimate based on self-reported financial information — no credit pull. Pre-approval involves a full credit check and document review by a lender. Pre-approval carries more weight with sellers and gives you a realistic budget for home shopping. Get pre-approved before house hunting to strengthen your offer.

🏘️ VA Loans

VA loans allow eligible veterans and active-duty service members to purchase with 0% down and no PMI. VA loans often have competitive rates. Eligibility requires military service (90+ days during wartime, 181+ days during peacetime, or 6+ years in Reserves/Guard). A $400K loan at 6% with 0% down yields ~$2,398/month P&I — no PMI for veterans.

📊 15-Year vs 30-Year Mortgages

A 15-year mortgage typically has higher monthly payments but saves hundreds of thousands in interest. Example: $350K at 5.9% for 15 years = $2,936/mo vs $2,212/mo for 30 years at 6.5% — $724 more monthly but saves ~$268K in interest. A 30-year offers lower payments and more cash-flow flexibility. Compare total cost before deciding based on your income stability and goals.

💡 Extra Payment Impact

Even $100–200 extra per month toward principal can cut years off your mortgage and save tens of thousands in interest. On a $350K loan at 6.5%, adding $200/month extra pays off ~5 years early and saves ~$68K in interest. Apply extra to principal only — specify "principal only" when making payments. Use the Extra Payment Impact chart above to see the difference.