Mortgage calculator
Enter your home price, down payment, interest rate and loan term to see your monthly payment breakdown including principal, interest, taxes and insurance.
What is a mortgage calculator?
A mortgage calculator tells you what a home will actually cost you each month — principal and interest, plus property tax and insurance — and shows how the split between interest and principal shifts over the life of the loan. Move the sliders to model different prices, down payments, and rates side by side.
The full breakdown.
| Year | Principal paid | Interest paid | Remaining | Interest share |
|---|---|---|---|---|
| Y01 | $3,577 | $20,695 | $316,423 | 85% |
| Y02 | $3,816 | $20,455 | $312,607 | 84% |
| Y03 | $4,072 | $20,200 | $308,535 | 83% |
| Y04 | $4,345 | $19,927 | $304,191 | 82% |
| Y05 | $4,636 | $19,636 | $299,555 | 81% |
| Y06 | $4,946 | $19,325 | $294,609 | 80% |
| Y07 | $5,277 | $18,994 | $289,332 | 78% |
| Y08 | $5,631 | $18,641 | $283,701 | 77% |
| Y09 | $6,008 | $18,264 | $277,694 | 75% |
| Y10 | $6,410 | $17,861 | $271,284 | 74% |
| Y11 | $6,839 | $17,432 | $264,444 | 72% |
| Y12 | $7,297 | $16,974 | $257,147 | 70% |
| Y13 | $7,786 | $16,485 | $249,361 | 68% |
| Y14 | $8,308 | $15,964 | $241,053 | 66% |
| Y15 | $8,864 | $15,407 | $232,189 | 63% |
| Y16 | $9,458 | $14,814 | $222,732 | 61% |
| Y17 | $10,091 | $14,180 | $212,641 | 58% |
| Y18 | $10,767 | $13,505 | $201,874 | 56% |
| Y19 | $11,488 | $12,784 | $190,386 | 53% |
| Y20 | $12,257 | $12,014 | $178,129 | 49% |
| Y21 | $13,078 | $11,193 | $165,051 | 46% |
| Y22 | $13,954 | $10,317 | $151,097 | 43% |
| Y23 | $14,888 | $9,383 | $136,208 | 39% |
| Y24 | $15,886 | $8,386 | $120,323 | 35% |
| Y25 | $16,949 | $7,322 | $103,373 | 30% |
| Y26 | $18,085 | $6,187 | $85,289 | 25% |
| Y27 | $19,296 | $4,976 | $65,993 | 21% |
| Y28 | $20,588 | $3,683 | $45,405 | 15% |
| Y29 | $21,967 | $2,305 | $23,438 | 9% |
| Y30 | $23,438 | $833 | $0 | 3% |
The payment formula behind every mortgage.
Every fixed-rate mortgage payment is calculated with the same formula. It spreads your principal evenly across the loan term while front-loading interest — so early payments are mostly interest and later payments are mostly principal.
Property taxes, homeowners insurance, and PMI are added on top of this base payment. They don't shrink over time like the interest component does.
- M
- Monthly payment — principal + interest portion of your monthly bill
- P
- Loan principal — home price minus your down payment
- r
- Monthly rate — annual interest rate divided by 12
- n
- Total payments — loan term in years multiplied by 12
Six ways to actually use these numbers.
Aim for under 28% of gross income.
If PITI plus HOA exceeds 28% of your pretax monthly income, you're likely house-poor. Lenders will go higher; that doesn't mean you should.
Run the numbers at +1%.
Rate volatility is the single biggest variable. Always model your payment at a rate 0.5-1% above today's, so a slow lock doesn't break the budget.
Don't sleep on tax + insurance.
Property tax and homeowners insurance often add $400-800/mo to a payment. The headline P&I figure understates real cost.
Extra $200/mo = years off.
$200/month extra on a 30-yr loan at 6.5% knocks roughly 6 years off and saves $80K+ in interest. Try it in the calculator.
20% down isn't always optimal.
Putting more down avoids PMI but reduces liquidity. Run the scenario at 10% with PMI and invest the difference — sometimes that wins.
Refi math is sensitivity, not certainty.
Refinancing usually pays off if you'll save more in interest than the closing costs over your expected stay. Use the calc to check your specific break-even.