Why is so much of my early payment interest?

Interest is charged on the outstanding balance, and early on the balance is at its largest. On a $300K loan at 6.5%, month 1 charges $1,625 interest against a $1,896 payment. As the balance shrinks, the interest share falls and principal accelerates — the curve is built into the formula, not a lender trick.

How do extra principal payments change the schedule?

Every extra dollar goes straight to the balance, which cuts the interest charged in all future months and shortens the term. One extra monthly payment per year on a 30-year mortgage typically pays it off around 4-5 years early. Tell your servicer to apply extras to principal — some default to prepaying next month's payment instead.

What's the difference between amortization and simple interest?

An amortized loan charges interest monthly on the declining balance and levels the payment over the term. Simple-interest quotes (like 'borrow $10K, pay back $11K') ignore timing. The amortization schedule is the ground truth for almost all mortgages, auto loans, student loans, and personal loans in the US.

Why doesn't my lender's payoff amount match the schedule's balance?

The payoff quote adds accrued interest since your last payment (per-diem interest), and possibly small fees. The schedule shows the balance immediately after each on-time payment. They converge on payment day and drift in between — always request an official payoff quote before wiring money.

Does this work for biweekly payment plans?

Not directly — the schedule is monthly. The biweekly effect (26 half-payments = 13 full payments a year) is approximately the same as adding 1/12 of your payment as extra principal each month. Model it that way, or just note that true biweekly plans on a 30-year mortgage typically shave 4-6 years off the term.

Money & Finance · Free tool

Amortization Calculator

Full amortization schedule for any fixed-rate loan. Principal vs interest split per payment, total interest, CSV export.

Updated June 2026

Loan amountInterest rate (% annual)Term (years)

Monthly payment

$1,896.20

Total paid

$682,633.47

Total interest

$382,633.47

Amortization schedule (year-end)

Month	Principal	Interest	Balance
1	$271.20	$1,625.00	$299,728.80
12	$287.81	$1,608.40	$296,646.82
24	$307.08	$1,589.12	$293,069.08
36	$327.65	$1,568.55	$289,251.73
48	$349.59	$1,546.61	$285,178.72
60	$373.01	$1,523.20	$280,832.93
72	$397.99	$1,498.22	$276,196.10
84	$424.64	$1,471.56	$271,248.73
96	$453.08	$1,443.13	$265,970.03
108	$483.42	$1,412.78	$260,337.81
120	$515.80	$1,380.41	$254,328.38
132	$550.34	$1,345.86	$247,916.49
144	$587.20	$1,309.00	$241,075.18
156	$626.53	$1,269.68	$233,775.70
168	$668.48	$1,227.72	$225,987.36
180	$713.25	$1,182.95	$217,677.42
192	$761.02	$1,135.18	$208,810.95
204	$811.99	$1,084.21	$199,350.68
216	$866.37	$1,029.83	$189,256.83
228	$924.39	$971.81	$178,486.98
240	$986.30	$909.90	$166,995.85
252	$1,052.36	$843.85	$154,735.14
264	$1,122.83	$773.37	$141,653.30
276	$1,198.03	$698.17	$127,695.36
288	$1,278.27	$617.94	$112,802.62
300	$1,363.87	$532.33	$96,912.49
312	$1,455.21	$440.99	$79,958.16
324	$1,552.67	$343.53	$61,868.38
336	$1,656.66	$239.55	$42,567.08
348	$1,767.61	$128.60	$21,973.15
360	$1,885.99	$10.22	$0.00

Standard fixed-rate amortization formula. Doesn’t include taxes, insurance, PMI, or HOA — see our mortgage calculator for the all-in monthly figure.

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What it does

Full amortization schedule for any fixed-rate loan. Principal vs interest split per payment, total interest, CSV export. Money math compounds: small percentage differences over years become large dollar differences.

Federal Reserve rate decisions, tax law changes, and inflation shifts all change the optimal answer year-over-year. The gap between “rough estimate” and “defensible number” is exactly where good tooling earns its keep — the math is reproducible, but knowing which inputs matter and what the result means is half the work.

Always cross-check calculator output against published sources (IRS.gov for taxes, FRED for rates, Bankrate for current product pricing). A common pitfall: comparing pre-tax to after-tax numbers without normalizing. Treat the tool’s output as a starting point and validate against authoritative sources for any consequential decision.

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Example input & output

Input

Loan: $300,000
Rate: 6.5%
Term: 30 years

Output

Monthly payment: $1,896.20
Total paid: $682,633
Total interest: $382,633

Month 1 splits into $1,625 interest and only $271 principal — early payments are mostly interest. The split doesn't reach 50/50 until roughly year 20 on this loan.

How to use it

Enter the loan amount, annual interest rate, and term in years.
Read the fixed monthly payment, total paid, and total interest at the top.
Scan the schedule — year-end rows show by default; toggle 'show all' for every month.
Download the CSV if you want the full schedule in a spreadsheet.

How it works

The payment comes from the standard amortization formula: PMT = L × r ÷ (1 − (1 + r)⁻ⁿ), where L is the loan amount, r the monthly rate (annual ÷ 12), and n the number of months. Each month the tool charges interest on the remaining balance (balance × r), applies the rest of the payment to principal, and repeats. The payment never changes — the interest/principal split inside it does.

Common mistakes when using this tool

Comparing payment instead of total interest. A longer term always looks cheaper monthly and costs far more overall — the totals row is the honest comparison.
Entering APR with fees baked in. The schedule wants the note rate. APR includes closing costs and will slightly overstate the payment.
Forgetting escrow. This is principal + interest only. A real mortgage payment adds property tax and insurance — see the mortgage calculator for PITI.

When to use this tool

Before signing any fixed-rate loan — see exactly how much of each payment is interest, month by month.
Answering 'how much principal will I have paid by year 5?' — the question most mortgage calculators don't surface.
Comparing terms: rerun 15 vs 30 years and watch total interest roughly triple on the longer term.
Planning extra payments — the schedule shows the balance any prepayment would attack.

When not to use it

Adjustable-rate loans — the schedule assumes one fixed rate for the whole term.
Interest-only periods, balloon payments, or negative amortization products — different payment structures entirely.
Credit cards — revolving debt has no fixed term; use the debt payoff calculator.

Common use cases

Homebuyer checking how slowly a 30-year mortgage builds equity in the first five years.
Borrower deciding whether a $200/month extra principal payment is worth it before committing.
Refinance analysis: comparing remaining interest on the current loan vs a new loan's full schedule.
Car or personal loan sanity check — verifying the lender's quoted payment against the standard formula.

Frequently asked questions

Why is so much of my early payment interest?: Interest is charged on the outstanding balance, and early on the balance is at its largest. On a $300K loan at 6.5%, month 1 charges $1,625 interest against a $1,896 payment. As the balance shrinks, the interest share falls and principal accelerates — the curve is built into the formula, not a lender trick.
How do extra principal payments change the schedule?: Every extra dollar goes straight to the balance, which cuts the interest charged in all future months and shortens the term. One extra monthly payment per year on a 30-year mortgage typically pays it off around 4-5 years early. Tell your servicer to apply extras to principal — some default to prepaying next month's payment instead.
What's the difference between amortization and simple interest?: An amortized loan charges interest monthly on the declining balance and levels the payment over the term. Simple-interest quotes (like 'borrow $10K, pay back $11K') ignore timing. The amortization schedule is the ground truth for almost all mortgages, auto loans, student loans, and personal loans in the US.
Why doesn't my lender's payoff amount match the schedule's balance?: The payoff quote adds accrued interest since your last payment (per-diem interest), and possibly small fees. The schedule shows the balance immediately after each on-time payment. They converge on payment day and drift in between — always request an official payoff quote before wiring money.
Does this work for biweekly payment plans?: Not directly — the schedule is monthly. The biweekly effect (26 half-payments = 13 full payments a year) is approximately the same as adding 1/12 of your payment as extra principal each month. Model it that way, or just note that true biweekly plans on a 30-year mortgage typically shave 4-6 years off the term.

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