Calculate fixed-rate monthly loan and mortgage principal-and-interest payments, total interest cost, extra payment payoff acceleration, and a yearly amortization schedule with expandable monthly details.
Each year displays aggregate totals by default. Click any year row to expand its month-by-month ledger.
| Month | Starting Balance | Total Payment | Principal | Extra Principal | Interest | Ending Balance |
|---|---|---|---|---|---|---|
| M1 | $30,000.00 | $586.98 | $424.48 | $0.00 | $162.50 | $29,575.52 |
| M2 | $29,575.52 | $586.98 | $426.78 | $0.00 | $160.20 | $29,148.74 |
| M3 | $29,148.74 | $586.98 | $429.09 | $0.00 | $157.89 | $28,719.65 |
| M4 | $28,719.65 | $586.98 | $431.42 | $0.00 | $155.56 | $28,288.23 |
| M5 | $28,288.23 | $586.98 | $433.75 | $0.00 | $153.23 | $27,854.48 |
| M6 | $27,854.48 | $586.98 | $436.10 | $0.00 | $150.88 | $27,418.38 |
| M7 | $27,418.38 | $586.98 | $438.46 | $0.00 | $148.52 | $26,979.92 |
| M8 | $26,979.92 | $586.98 | $440.84 | $0.00 | $146.14 | $26,539.08 |
| M9 | $26,539.08 | $586.98 | $443.23 | $0.00 | $143.75 | $26,095.85 |
| M10 | $26,095.85 | $586.98 | $445.63 | $0.00 | $141.35 | $25,650.22 |
| M11 | $25,650.22 | $586.98 | $448.04 | $0.00 | $138.94 | $25,202.18 |
| M12 | $25,202.18 | $586.98 | $450.47 | $0.00 | $136.51 | $24,751.71 |
| Month | Starting Balance | Total Payment | Principal | Extra Principal | Interest | Ending Balance |
|---|---|---|---|---|---|---|
| M13 | $24,751.71 | $586.98 | $452.91 | $0.00 | $134.07 | $24,298.80 |
| M14 | $24,298.80 | $586.98 | $455.36 | $0.00 | $131.62 | $23,843.44 |
| M15 | $23,843.44 | $586.98 | $457.83 | $0.00 | $129.15 | $23,385.61 |
| M16 | $23,385.61 | $586.98 | $460.31 | $0.00 | $126.67 | $22,925.30 |
| M17 | $22,925.30 | $586.98 | $462.80 | $0.00 | $124.18 | $22,462.50 |
| M18 | $22,462.50 | $586.98 | $465.31 | $0.00 | $121.67 | $21,997.19 |
| M19 | $21,997.19 | $586.98 | $467.83 | $0.00 | $119.15 | $21,529.36 |
| M20 | $21,529.36 | $586.98 | $470.36 | $0.00 | $116.62 | $21,059.00 |
| M21 | $21,059.00 | $586.98 | $472.91 | $0.00 | $114.07 | $20,586.09 |
| M22 | $20,586.09 | $586.98 | $475.47 | $0.00 | $111.51 | $20,110.62 |
| M23 | $20,110.62 | $586.98 | $478.05 | $0.00 | $108.93 | $19,632.57 |
| M24 | $19,632.57 | $586.98 | $480.64 | $0.00 | $106.34 | $19,151.93 |
| Month | Starting Balance | Total Payment | Principal | Extra Principal | Interest | Ending Balance |
|---|---|---|---|---|---|---|
| M25 | $19,151.93 | $586.98 | $483.24 | $0.00 | $103.74 | $18,668.69 |
| M26 | $18,668.69 | $586.98 | $485.86 | $0.00 | $101.12 | $18,182.83 |
| M27 | $18,182.83 | $586.98 | $488.49 | $0.00 | $98.49 | $17,694.34 |
| M28 | $17,694.34 | $586.98 | $491.14 | $0.00 | $95.84 | $17,203.20 |
| M29 | $17,203.20 | $586.98 | $493.80 | $0.00 | $93.18 | $16,709.40 |
| M30 | $16,709.40 | $586.98 | $496.47 | $0.00 | $90.51 | $16,212.93 |
| M31 | $16,212.93 | $586.98 | $499.16 | $0.00 | $87.82 | $15,713.77 |
| M32 | $15,713.77 | $586.98 | $501.86 | $0.00 | $85.12 | $15,211.91 |
| M33 | $15,211.91 | $586.98 | $504.58 | $0.00 | $82.40 | $14,707.33 |
| M34 | $14,707.33 | $586.98 | $507.32 | $0.00 | $79.66 | $14,200.01 |
| M35 | $14,200.01 | $586.98 | $510.06 | $0.00 | $76.92 | $13,689.95 |
| M36 | $13,689.95 | $586.98 | $512.83 | $0.00 | $74.15 | $13,177.12 |
| Month | Starting Balance | Total Payment | Principal | Extra Principal | Interest | Ending Balance |
|---|---|---|---|---|---|---|
| M37 | $13,177.12 | $586.98 | $515.60 | $0.00 | $71.38 | $12,661.52 |
| M38 | $12,661.52 | $586.98 | $518.40 | $0.00 | $68.58 | $12,143.12 |
| M39 | $12,143.12 | $586.98 | $521.20 | $0.00 | $65.78 | $11,621.92 |
| M40 | $11,621.92 | $586.98 | $524.03 | $0.00 | $62.95 | $11,097.89 |
| M41 | $11,097.89 | $586.98 | $526.87 | $0.00 | $60.11 | $10,571.02 |
| M42 | $10,571.02 | $586.98 | $529.72 | $0.00 | $57.26 | $10,041.30 |
| M43 | $10,041.30 | $586.98 | $532.59 | $0.00 | $54.39 | $9,508.71 |
| M44 | $9,508.71 | $586.98 | $535.47 | $0.00 | $51.51 | $8,973.24 |
| M45 | $8,973.24 | $586.98 | $538.37 | $0.00 | $48.61 | $8,434.87 |
| M46 | $8,434.87 | $586.98 | $541.29 | $0.00 | $45.69 | $7,893.58 |
| M47 | $7,893.58 | $586.98 | $544.22 | $0.00 | $42.76 | $7,349.36 |
| M48 | $7,349.36 | $586.98 | $547.17 | $0.00 | $39.81 | $6,802.19 |
| Month | Starting Balance | Total Payment | Principal | Extra Principal | Interest | Ending Balance |
|---|---|---|---|---|---|---|
| M49 | $6,802.19 | $586.98 | $550.13 | $0.00 | $36.85 | $6,252.06 |
| M50 | $6,252.06 | $586.98 | $553.11 | $0.00 | $33.87 | $5,698.95 |
| M51 | $5,698.95 | $586.98 | $556.11 | $0.00 | $30.87 | $5,142.84 |
| M52 | $5,142.84 | $586.98 | $559.12 | $0.00 | $27.86 | $4,583.72 |
| M53 | $4,583.72 | $586.98 | $562.15 | $0.00 | $24.83 | $4,021.57 |
| M54 | $4,021.57 | $586.98 | $565.20 | $0.00 | $21.78 | $3,456.37 |
| M55 | $3,456.37 | $586.98 | $568.26 | $0.00 | $18.72 | $2,888.11 |
| M56 | $2,888.11 | $586.98 | $571.34 | $0.00 | $15.64 | $2,316.77 |
| M57 | $2,316.77 | $586.98 | $574.43 | $0.00 | $12.55 | $1,742.34 |
| M58 | $1,742.34 | $586.98 | $577.54 | $0.00 | $9.44 | $1,164.80 |
| M59 | $1,164.80 | $586.98 | $580.67 | $0.00 | $6.31 | $584.13 |
| M60 | $584.13 | $587.29 | $584.13 | $0.00 | $3.16 | $0.00 |
For a fixed-rate loan with principal P, monthly periodic interest rate r = APR / 12, and n monthly installments, the scheduled level monthly payment is PMT = P × [r(1 + r)^n] / [(1 + r)^n − 1]. When APR = 0%, the monthly payment is simply P / n. Each month, interest is calculated on the remaining balance (I_k = B_{k−1} × r) and the rest of the payment reduces principal.
The engine computes the penny-rounded scheduled monthly payment and runs a month-by-month amortization ledger. At month k, interest I_k = round2(B_{k−1} × r) is accrued first; scheduled principal is PMT − I_k, plus any recurring monthly or one-time extra principal payment clamped to the remaining balance. On the final installment, any penny-rounding residual is automatically adjusted so the ending balance reaches $0.00 exactly.
A borrower finances $30,000 at 6.5% nominal APR over 60 months with $0 extra payments (monthly periodic rate r = 0.065 / 12 = 0.00541667).
Scheduled Monthly Payment: $586.98 | Total Principal: $30,000.00 | Total Interest: $5,219.11 | Total Paid: $35,219.11 over 60 months.
Adding $100/month in extra principal to the same $30,000, 6.5% APR, 60-month loan ($686.98 total monthly outlay).
Payoff Duration: 50 months (10 months saved) | Actual Total Interest: $4,323.04 | Total Interest Saved: $896.07.
Given loan principal P, monthly periodic interest rate r = (APR / 100) / 12, and total months n, the standard level monthly payment is PMT = P × [r(1 + r)^n] / [(1 + r)^n − 1]. If the interest rate is 0%, the formula simplifies to PMT = P / n.
Even though your scheduled monthly payment stays constant, each month's interest charge is calculated by multiplying your remaining loan balance by the monthly interest rate (I_k = Balance × r). As your principal balance shrinks each month, less interest accrues in the following month, allowing a larger share of your fixed payment to go directly toward principal.
Because monthly payments and monthly interest charges are rounded to the nearest cent ($0.01) at each of the n installments, small sub-cent rounding differences accumulate over the life of the loan. On the final payment, lenders adjust the principal portion to match the exact remaining balance so the loan closes at $0.00.
An extra principal payment directly reduces your remaining loan balance in the month it is paid. Because every subsequent month's interest is calculated on that smaller balance, less interest accrues for the rest of the loan, and more of your regular fixed payment goes toward principal—accelerating your payoff date.