15-Year Mortgage Calculator
The fastest traditional path to a paid-off house. Calculate your precise monthly payments and discover exactly how much money you will save in interest by choosing a 15-year fixed-rate mortgage over a traditional 30-year term.
Last updated: March 2, 2026
15-year mortgages often command interest rates 0.5% to 1.0% lower than 30-year mortgages, making the math even more heavily weighted in the buyer's favor if cash flow permits.
The 15-Year vs. 30-Year Dilemma
Deciding between the two most common mortgage term lengths is one of the biggest financial decisions you'll make. Here is how they stack up against each other for a hypothetical $400,000 loan.
15-Year Fixed Mortgage
- Pros: Builds home equity incredibly fast. Secures a significantly lower interest rate. You will literally save hundreds of thousands of dollars in interest over the life of the loan.
- Cons: A rigid, permanently high monthly payment. Leaves less monthly cash flow available for investing in the stock market, retirement accounts, or general emergencies.
Hypothetical $400k Loan at 5.5%
30-Year Fixed Mortgage
- Pros: Provides exactly half the required monthly payment of a 15-year loan, keeping your debt-to-income ratio low. Maximum flexibility—you can choose to pay extra principal in good months, but fall back on the low payment if you lose your job.
- Cons: For the first 10 years, almost all of your monthly payment goes pure to bank interest, building equity at a snail's pace. The total cost of the home ends up being staggeringly high.
Hypothetical $400k Loan at 6.0% (Rates are higher)
How Amortization Actually Works
When a bank structures a mortgage, the monthly payment is completely identical for the entire lifespan of the loan. This is called 'amortization'. However, the ratio of that payment that goes toward Principal vs. Interest changes wildly every single month.
In a 30-year mortgage, it takes roughly 15 years before the crossover point happens where your payment actively starts paying down more principal than interest.
In a 15-year mortgage, because your mandatory monthly payment is so high, you brute-force that crossover point within the first few years, attacking the principal furiously and preventing the interest from constantly compounding against you.
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