Tools · Home Buying
Mortgage Calculator
Compare 15, 20, 30, and a fictional 50-year term side by side, see what tax, insurance, and PMI actually add to the monthly number, and see why stretching the term past 30 years stops paying off.
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Purchase price before down payment
Enter an amount greater than $0
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20% of home price
Enter an amount of $0 or more, less than the home price
%
Shorter terms carry lower risk for the lender, so this is normally the cheapest rate on the board
Enter a rate between 0% and 20%
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The 20-year rate is interpolated between this and the 15-year rate; the fictional 50-year term below adds 0.75% on top of this
Enter a rate between 0% and 20%
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Optional. Applied straight to principal every month
Enter an amount of $0 or more
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Can be $0 if you'd rather see principal & interest alone
Enter an amount of $0 or more
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Homeowner's insurance premium, billed yearly
Enter an amount of $0 or more
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Leave at $0 if your down payment is 20%+. Modeled as dropping off once equity hits 20%
Enter an amount of $0 or more
📌 The default rates above (5.95% / 6.65%) are a static snapshot: Freddie Mac's Primary Mortgage Market Survey average for the week of August 20, 2026. They don't update automatically. Swap in whatever rate a lender actually quotes you before using this for a real decision.
📋 Term Comparison
| Term | Rate | Monthly P&I | Est. Total Monthly* | Payoff Time | Total Interest | Total Cost |
|---|
*Includes tax, insurance, and PMI (while your equity is under 20%). Payoff time reflects any extra monthly payment.
Why is there a 50-year term? No lender actually sells one. It's included on purpose, priced at your 30-year rate plus a 0.75% markup to reflect the extra risk a lender would charge for something this long. Stretching the term that far barely lowers the monthly payment past what 30 years already gets you, while total interest and total cost keep climbing for another two decades. It's here to make that diminishing return visible, not to recommend it.
📝 Methodology & Assumptions
This calculator models a standard fixed-rate, fully amortizing loan:
- Rate: You enter the 15-year and 30-year rates directly. The 20-year rate is interpolated between them (real lenders usually price it that way too). The fictional 50-year term takes the 30-year rate and adds a flat 0.75% markup, since no real lender prices one.
- PMI: Modeled as a flat monthly amount that drops off automatically once your scheduled principal balance falls to 80% of the home price, the common threshold for conventional loans. It does not model lender-paid PMI or FHA mortgage insurance, which work differently.
- Extra Payments: Applied entirely to principal every month, shortening the loan and cutting total interest. The comparison table's "Payoff Time" already reflects this.
- Tax & Insurance: Treated as flat annual amounts spread evenly across twelve months. Neither is modeled as increasing over time, real bills usually do.
- No Closing Costs, No Points: This models the ongoing payment, not the cost of originating the loan.
🔒 Nothing typed into this calculator is collected, transmitted, or stored anywhere. Every calculation runs in your browser and disappears the moment you close the tab.