KokoroFlow calculator
Estimate a monthly principal and interest payment for a home loan.
Last updated: October 2026
Estimate monthly principal and interest, total interest, and the effect of extra payments.
This calculator estimates principal and interest only. It does not include property tax, homeowners insurance, HOA fees, mortgage insurance, or closing costs.
Use this as a quick planning estimate, not as financial advice.
It estimates a monthly principal-and-interest payment from a home price, down payment, interest rate, and loan term, and shows how an extra monthly payment toward principal could shorten the payoff timeline and reduce total interest. It gives a quick planning figure before you talk to a lender.
A $400,000 home with an $80,000 down payment (a $320,000 loan) at 6.75% APR over 30 years comes to a scheduled principal-and-interest payment of about $2,075.51 a month, with roughly $427,000 in total interest paid over the full term. Adding even $200 extra toward principal each month can meaningfully shorten the payoff timeline and reduce total interest paid — the calculator's extra-payment field shows this effect directly.
No. This calculator estimates principal and interest only. Property tax, homeowners insurance, HOA fees, and mortgage insurance (PMI) are separate costs that typically get added to a full monthly housing payment.
Extra principal payments reduce the loan balance faster, which reduces the interest that accrues on it going forward. Even a modest consistent extra payment can shave years off a 30-year term and save a meaningful amount in total interest.
Not necessarily — many loan programs allow smaller down payments, though a down payment below 20% often triggers private mortgage insurance (PMI), which is not included in this estimate.
Yes — try 15 years versus 30 years at the same rate to compare the monthly payment against total interest paid, which is a common trade-off when choosing a mortgage term.
In depth
The payment above is principal and interest (P&I) only, the part set by your loan amount, rate and term. This section explains how that number is calculated, how much the rate and term change it, what an extra payment really saves, and what else will show up on your monthly housing bill.
For a fixed-rate loan, the monthly payment is P × r ÷ (1 − (1 + r)−n), where P is the loan amount, r is the annual rate divided by 12, and n is the number of monthly payments. The payment stays the same for the life of the loan, but its mix changes: early payments are mostly interest. On a $320,000 loan at 6.75%, the first month's interest is $1,800 and only about $276 reduces the balance.
| Rate and term | Monthly P&I | Total interest |
|---|---|---|
| 6.25%, 30 years | $1,970.30 | about $389,000 |
| 6.75%, 30 years | $2,075.51 | about $427,000 |
| 7.25%, 30 years | $2,182.96 | about $466,000 |
| 6.75%, 15 years | $2,831.71 | about $190,000 |
Half a percentage point moves the payment by roughly $105 a month here, and it moves total interest by almost $40,000 over 30 years. In practice, 15-year loans often carry lower rates than 30-year loans, which widens the gap further.
Extra principal reduces the balance that future interest is charged on. Adding $200 a month to the 6.75% 30-year example pays the loan off in about 23 years and 4 months instead of 30 years, and cuts total interest from about $427,000 to about $315,000. Before prepaying, confirm with your servicer that extra amounts are applied to principal and that the loan has no prepayment penalty.
The interest rate sets your payment. The APR also includes certain lender fees and points, which makes it more useful for comparing loan offers. When you shop, compare Loan Estimates from several lenders on both numbers.
Figures checked October 2026. Tax rules change; confirm with the linked official pages before filing or signing anything.