Mortgage Comparison Calculator — 15-Year vs 30-Year with PMI, Tax

How 15-Year vs 30-Year Mortgage Works

M = P × [r(1+r)^n] / [(1+r)^n - 1] where M = monthly payment, P = principal, r = monthly rate, n = months

This calculator compares a 15-year vs 30-year mortgage side by side, accounting for different interest rates, property taxes, insurance, and PMI. The shorter term almost always has a lower rate but higher monthly payment, while the longer term has lower payments but dramatically more total interest. The key insight: the "savings" from a 15-year term is typically hundreds of thousands of dollars, but only if you can afford the higher monthly payment.

PMI

Private Mortgage Insurance — Required when down payment is less than 20%. Typically 0.3-1.5% of the loan amount annually, paid monthly until you reach 20% equity.

LTV

Loan-to-Value Ratio — The loan amount divided by the home price. LTV above 80% triggers PMI requirement.

Escrow

Escrow Payment — Monthly payment that includes taxes and insurance held in escrow by the lender, paid on your behalf when due.

How to Use

1. Enter the home price and your down payment amount.
2. Enter current 15-year and 30-year mortgage rates.
3. Optionally add property tax rate and annual insurance for a true monthly comparison.
4. If down payment is under 20%, enter your estimated PMI rate.
5. Compare the monthly payment and total cost side by side.

Quick Reference

Common Uses

• •Compare a 15-year versus 30-year mortgage side by side to see the trade-off between lower monthly payments and total interest savings.
• •Determine whether the higher monthly payment of a shorter mortgage term is worth the hundreds of thousands of dollars in interest saved over the loan life.
• •Factor in PMI, property taxes, and insurance to get a true monthly payment comparison between different mortgage options.

Understanding the Result

The 15-year vs 30-year mortgage decision is one of the most consequential financial choices a homebuyer makes. A 15-year mortgage typically offers a lower interest rate (often 0.5-1% lower) and builds equity twice as fast, but requires a significantly higher monthly payment. Over the life of the loan, the 30-year mortgage can cost $100,000-$300,000+ more in interest. However, the 30-year offers lower monthly payments and more flexibility — the difference can be invested elsewhere. This calculator gives you the exact numbers for your specific scenario so you can make an informed tradeoff.

Worked Examples

Frequently Asked Questions

Is a 15-year mortgage always better?

Not always. A 15-year mortgage saves on total interest but requires higher monthly payments. If the payment difference would strain your budget or prevent you from investing in retirement accounts (especially with employer match), the 30-year may be better. You can always make extra principal payments on a 30-year to effectively shorten the term.

How is PMI calculated?

PMI (Private Mortgage Insurance) typically costs 0.3% to 1.5% of the original loan amount per year, paid monthly. It is required when your down payment is less than 20% of the home price. Once you reach 20% equity, you can request PMI cancellation.

Should I include property taxes in my comparison?

Yes — property taxes and insurance are unavoidable costs of homeownership. Including them gives you the true monthly payment difference between the two loan options. Property tax rates vary significantly by location, from under 0.5% in some areas to over 2.5% in others.

How accurate is this calculator for real-world use?

This calculator uses standard mathematical formulas and provides estimates based on the inputs you enter. For financial decisions, always verify results with a qualified professional and check against official statements or lender-provided figures which may include additional factors not modeled here.

Pro Tips

• →The 15-year rate is typically 0.5%–1% lower than the 30-year rate. This rate spread is free money — but only if you qualify and can afford the higher monthly payment. Run both rates at current market levels, not guesstimates.
• →PMI falls off automatically at 78% LTV or can be requested at 80%. On a 15-year loan, you hit 80% LTV roughly twice as fast because more of each payment goes to principal. Factor in the PMI removal date when comparing total costs.
• →Consider the "30-year + prepay" strategy: take the 30-year for the lower required payment, but make extra principal payments equivalent to the 15-year amount. You get most of the interest savings of the 15-year with the flexibility to drop back to the lower payment if finances tighten.
• →If you invest the monthly savings from the 30-year (instead of spending it), you may come out ahead of the 15-year even after paying more interest. At a 7% stock market return, investing the $592/month difference from Example 1 for 30 years yields about $720,000 — more than the $324K in total payment savings from the 15-year.

Limitations to Know

• •Rate quotes are estimates. Actual mortgage rates depend on your credit score, loan type (conventional, FHA, VA, jumbo), points paid, and the specific lender. Always get a Loan Estimate from at least 3 lenders before deciding.
• •PMI is simplified as a flat annual percentage. In reality, PMI rates vary by credit score, LTV, and mortgage insurer. FHA loans use MIP (Mortgage Insurance Premium) with different rules, including upfront premiums and potentially lifetime MIP.
• •Property taxes are assumed constant. In reality, property taxes can increase significantly after purchase if the home is reassessed at the new purchase price. Some states cap annual increases (CA Prop 13), others do not.
• •This comparison does not factor in the opportunity cost of the larger down payment, tax deductibility of mortgage interest (which changed significantly under the TCJA), closing costs, or the fact that 15-year loans may have slightly different underwriting requirements and debt-to-income ratio limits.

Sources

• Consumer Financial Protection Bureau
• Investopedia