📅 Loan & Mortgage Amortization Schedule
A loan amortization schedule generator producing every payment row, not a summary. Download as CSV for Excel, print it, compare biweekly payments.
Amortization Schedule (360 payments)
| Month | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| #1 (1y) | $1798.65 | $298.65 | $1500.00 | $299701 |
| #2 (1y) | $1798.65 | $300.14 | $1498.51 | $299401 |
| #3 (1y) | $1798.65 | $301.65 | $1497.01 | $299100 |
| #4 (1y) | $1798.65 | $303.15 | $1495.50 | $298796 |
| #5 (1y) | $1798.65 | $304.67 | $1493.98 | $298492 |
| #6 (1y) | $1798.65 | $306.19 | $1492.46 | $298186 |
| #7 (1y) | $1798.65 | $307.72 | $1490.93 | $297878 |
| #8 (1y) | $1798.65 | $309.26 | $1489.39 | $297569 |
| #9 (1y) | $1798.65 | $310.81 | $1487.84 | $297258 |
| #10 (1y) | $1798.65 | $312.36 | $1486.29 | $296945 |
| #11 (1y) | $1798.65 | $313.92 | $1484.73 | $296631 |
| #12 (1y) | $1798.65 | $315.49 | $1483.16 | $296316 |
| #24 (2y) | $1798.65 | $334.95 | $1463.70 | $292405 |
| #36 (3y) | $1798.65 | $355.61 | $1443.04 | $288252 |
| #48 (4y) | $1798.65 | $377.55 | $1421.11 | $283844 |
| #60 (5y) | $1798.65 | $400.83 | $1397.82 | $279163 |
| #72 (6y) | $1798.65 | $425.55 | $1373.10 | $274194 |
| #84 (7y) | $1798.65 | $451.80 | $1346.85 | $268918 |
| #96 (8y) | $1798.65 | $479.67 | $1318.98 | $263317 |
| #108 (9y) | $1798.65 | $509.25 | $1289.40 | $257371 |
| #120 (10y) | $1798.65 | $540.66 | $1257.99 | $251057 |
| #132 (11y) | $1798.65 | $574.01 | $1224.64 | $244354 |
| #144 (12y) | $1798.65 | $609.41 | $1189.24 | $237238 |
| #156 (13y) | $1798.65 | $647.00 | $1151.65 | $229683 |
| #168 (14y) | $1798.65 | $686.91 | $1111.75 | $221662 |
| #180 (15y) | $1798.65 | $729.27 | $1069.38 | $213147 |
| #192 (16y) | $1798.65 | $774.25 | $1024.40 | $204106 |
| #204 (17y) | $1798.65 | $822.01 | $976.64 | $194507 |
| #216 (18y) | $1798.65 | $872.71 | $925.95 | $184316 |
| #228 (19y) | $1798.65 | $926.53 | $872.12 | $173497 |
| #240 (20y) | $1798.65 | $983.68 | $814.97 | $162011 |
| #252 (21y) | $1798.65 | $1044.35 | $754.30 | $149816 |
| #264 (22y) | $1798.65 | $1108.76 | $689.89 | $136869 |
| #276 (23y) | $1798.65 | $1177.15 | $621.50 | $123123 |
| #288 (24y) | $1798.65 | $1249.75 | $548.90 | $108530 |
| #300 (25y) | $1798.65 | $1326.84 | $471.82 | $93036 |
| #312 (26y) | $1798.65 | $1408.67 | $389.98 | $76587 |
| #324 (27y) | $1798.65 | $1495.56 | $303.10 | $59124 |
| #336 (28y) | $1798.65 | $1587.80 | $210.85 | $40583 |
| #348 (29y) | $1798.65 | $1685.73 | $112.92 | $20898 |
| #360 (30y) | $1798.65 | $1789.70 | $8.95 | $0 |
What Loan & Mortgage Amortization Schedule Does
An amortization schedule is the payment-by-payment breakdown of a loan: how much of each payment goes to interest, how much reduces the balance, and what is left owing afterwards. The payment stays constant on a fixed-rate loan, but the split between those two shifts every single month.
That shift is slower than almost everyone expects. On a $300,000 mortgage at 6% over 30 years, principal does not overtake interest until month 223 — more than 18 years in, 62% of the way through the term. Until then, most of what you pay is rent on the money.
This generator produces the complete schedule for every payment, not a summary. You can view milestones or all 360 rows, download the whole thing as CSV for Excel, or print it. It also compares monthly payments against biweekly, which on that same loan saves $74,436 and clears it five and a half years early.
How to Use Loan & Mortgage Amortization Schedule
- Input loan principal amount, annual interest rate, and term in years
- Review monthly principal and interest payment breakdown
- Click Copy CSV Schedule to import into Excel or Google Sheets
Formula Used by Loan & Mortgage Amortization Schedule
The payment, and how each one splits
M = P × [ r(1+r)^n ] ÷ [ (1+r)^n − 1 ] interest_k = balance_(k−1) × r principal_k = M − interest_k
- M
- The fixed monthly payment
- r
- Monthly rate: annual rate ÷ 12
- balance_(k−1)
- What you still owe before payment k. Interest is always charged on this, never on the original loan
Worked example
A $300,000 loan at 6% over 30 years.
- r = 0.06 ÷ 12 = 0.005, n = 360
- M = $1,798.65
- Payment 1 interest: 300,000 × 0.005 = $1,500.00
- Payment 1 principal: 1,798.65 − 1,500.00 = $298.65
Result: The first payment is 83% interest. Only $298.65 of $1,798.65 reduces the debt.
The biweekly trick — why it works
26 half-payments per year = 13 monthly payments
- half-payment
- M ÷ 2, paid every two weeks
- 26
- There are 26 fortnights in a year, not 24 — that is where the extra payment comes from
Worked example
The same $300,000 loan, paying $899.33 every two weeks instead of $1,798.65 monthly.
- 26 × 899.33 = $23,382 paid per year
- 12 × 1,798.65 = $21,584 under the monthly schedule
- The extra $1,798 a year goes entirely to principal
Result: Paid off in 24 years 6 months instead of 30, saving $74,436 in interest.
Where Each Payment Goes — $300,000 at 6% over 30 Years
Payment is $1,798.65 throughout. Only the split changes. Note how long it takes for principal to catch up.
| Payment | To interest | To principal | Balance remaining |
|---|---|---|---|
| 1 | $1,500.00 | $298.65 | $299,701 |
| 60 (year 5) | $1,397.82 | $400.83 | $279,163 |
| 120 (year 10) | $1,257.99 | $540.66 | $251,057 |
| 223 (crossover) | $894.94 | $903.71 | $178,084 |
| 240 (year 20) | $814.97 | $983.68 | $162,011 |
| 360 (final) | $8.95 | $1,789.70 | $0 |
Monthly vs Biweekly on the Same Loan
Identical rate and balance. The only difference is payment frequency, which quietly adds a 13th monthly payment each year.
| Schedule | Each payment | Paid per year | Payoff | Total interest |
|---|---|---|---|---|
| Monthly | $1,798.65 | $21,584 | 30 years | $347,515 |
| Biweekly | $899.33 | $23,382 | 24 yr 6 mo | $273,079 |
| Difference | — | +$1,798 | 5 yr 6 mo earlier | Saves $74,436 |
How the Term Changes the Interest Bill
Same $300,000 at 6%. Shortening the term raises the payment and collapses the total interest.
| Term | Monthly payment | Total interest | Total repaid |
|---|---|---|---|
| 30 years | $1,798.65 | $347,515 | $647,515 |
| 20 years | $2,149.29 | $215,830 | $515,830 |
| 15 years | $2,531.57 | $155,683 | $455,683 |
| 10 years | $3,330.62 | $99,674 | $399,674 |
How to Read Your Result
Why the early years feel like nothing is happening
Interest is charged on the outstanding balance, which starts at its maximum. In month one you are paying interest on the entire $300,000. As the balance falls the interest charge falls with it, so more of the same fixed payment goes to principal — and the effect accelerates. The last payment is 99.5% principal.
The crossover point is later than you think
On a 30-year loan at 6%, principal overtakes interest at month 223 — over 18 years. At a higher rate it is later still, because interest consumes more of each payment. This is the single most useful number to know before choosing a term, and no competing calculator surfaces it.
Biweekly is not magic, it is a 13th payment
Splitting the payment in half and paying every two weeks feels neutral, but there are 26 fortnights in a year, not 24. You end up paying one extra monthly payment annually, entirely against principal. You could achieve exactly the same result by paying 1/12 extra each month — check whether your servicer charges a fee to set up biweekly billing, because the benefit is free if you do it yourself.
Verify the schedule against your statement
Download the CSV and compare the balance after three or six payments against your real statement. If they diverge, something is different from what you entered — a fee rolled into the balance, a different compounding convention, or extra payments not being applied to principal. That is worth a phone call.
Limitations & Accuracy Notes
- This models a fixed-rate, fully amortizing loan with equal monthly payments. Adjustable-rate mortgages, interest-only periods, balloon payments and negative-amortization products behave differently.
- The schedule covers principal and interest only. Property tax, insurance, PMI and HOA dues are not included, so it will not match an escrowed mortgage statement total.
- Fees are excluded — origination, closing costs, and any prepayment penalty.
- The biweekly comparison assumes your lender applies each half-payment on receipt. Some servicers hold the first half until the second arrives, which removes most of the benefit; some also charge a setup fee for biweekly billing.
- Interest is computed on a simple monthly-periodic-rate basis. Some lenders use daily accrual or a 360-day year convention, which shifts figures by small amounts.
- This is arithmetic for planning, not a loan offer or financial advice.
Frequently Asked Questions
What is a Loan Amortization Schedule?
Why does the interest payment decrease over time?
Why is so little of my early payment going to principal?
What is the crossover point?
Why does my lender's schedule differ slightly?
Does the schedule include tax and insurance?
Is my data stored?
References & Further Reading
- eCFR — 12 CFR Part 1026 (Regulation Z, Truth in Lending) — US rules on APR disclosure and the payment schedule lenders must provide
- Federal Reserve — Selected Interest Rates (H.15) — Benchmark rates for realistic assumptions