Loan Calculator
Monthly payment and amortization schedule by repayment type
Enter the loan amount, interest rate, and term to see the monthly payment and full amortization schedule for an equal-payment, equal-principal, or bullet (interest-only) loan — including a grace period and early repayment.
A bullet loan is interest-only for its whole term, so there's no separate grace period to set.
Amortization schedule
| # | Principal | Interest | Extra | Payment | Balance |
|---|
How to use & notes
- Equal payment: pays the same amount every month, weighted toward interest early on and toward principal later.
- Equal principal: the principal portion stays constant, so the total payment gradually decreases (heavier upfront).
- Bullet: pays interest only until maturity, then repays the full principal in one lump sum.
- A grace period pays interest only for that many months, then switches to the chosen method (not applicable to bullet).
- Early repayment models a single lump sum at one point in time. 'Shorten term' keeps the per-period payment unchanged and pays off sooner; 'lower payment' keeps the original term and reduces later payments instead.
- Real loans vary by day-count convention, fees, and preferential rates, so treat this as a reference estimate only.
Working…
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It hasn't frozen — the result will appear when the calculation finishes.
About Loan Calculator
This calculator builds a month-by-month schedule for three ways of repaying a loan: level payments (the standard amortizing loan in the US), equal principal installments, and interest-only with the full balance due at the end (a bullet or balloon). It can also add an interest-only period at the start and one extra lump-sum payment, applied either to shorten the term or to lower the monthly payment.
Interest each month is the remaining balance times the annual rate divided by 12, which is how most fixed-rate US mortgages are quoted. The tool does not include property taxes, homeowners insurance, PMI, or closing costs, so its payment is principal and interest only, not the full escrowed payment on a mortgage statement.
The same $300,000 loan, three ways
At 6.5% for 30 years, a level-payment loan costs $1,896 a month and $382,633 in total interest, more than the amount borrowed. Paying equal principal ($833 a month plus interest) starts at $2,458 and falls to $838 in the last month, and total interest drops to $293,313. Interest-only for 30 years with a $300,000 balloon at the end costs $585,000 in interest.
Equal-principal schedules are uncommon for US home loans but show up in some business and international loans. They show the basic rule: the faster the balance falls, the less interest you pay, because every month's interest is charged on what is still owed.
Why the first years feel like all interest
Of the first $1,896 payment, $1,625 is interest and only $271 reduces the balance. Over the whole first year you pay about $22,750, and only $3,353 of it is principal. The balance does not fall below half of the original amount until payment 257, more than 21 years in.
This is why selling or refinancing after five or seven years often leaves a larger payoff than people expect, and why an extra payment early in the loan saves far more interest than the same payment made late: it removes principal that would otherwise have been charged interest for decades.
Interest rate vs. APR
The rate you enter here is the note rate used to calculate interest. The APR on a US Loan Estimate is a different number: under the Truth in Lending Act it also spreads certain finance charges, such as points and many lender fees, over the life of the loan. Two offers with the same note rate can have different APRs, and APR is the better number for comparing offers. Use the note rate in this calculator.
Extra payments: shorter term or lower payment
Paying extra on a US mortgage normally shortens the term while the required payment stays the same. Lowering the payment instead usually requires a recast, which some lenders offer for a fee. The calculator models both. Before making extra payments, check your note for a prepayment penalty. Federal rules limit them on most residential mortgages, but some loans still have them.
Worked examples
$300,000 mortgage at 6.5%, 30 years
- Input
Principal 300,000 / 6.5% / 360 months- Output
Level payment $1,896/mo, interest $382,633 / Equal principal $2,458 falling to $838, interest $293,313 / Interest-only $1,625/mo, interest $585,000
Monthly rate is 0.5417%. Level payment = P·r·(1+r)^n / ((1+r)^n − 1).
What year one actually pays down
- Input
Same level-payment loan, months 1 to 12- Output
Interest ≈ $19,401, principal ≈ $3,353
About 85% of the first year's payments go to interest.
How to use it
- Enter the loan amount, annual interest rate, and term in months.
- Choose a repayment method and, if needed, an interest-only period.
- Turn on the extra payment, pick the month, amount, and mode to see the new payoff date and total interest.
Frequently asked questions
Why doesn't my payment match my mortgage statement?
Your statement usually includes escrow for property tax and insurance, and sometimes PMI. This tool shows principal and interest only.
Does it handle adjustable-rate mortgages?
Only one rate at a time. To approximate a rate reset, enter the balance at the reset as the new principal, the remaining months as the term, and the new rate.
Is it better to pay extra or invest the difference?
An extra payment earns exactly the loan's interest rate with no risk. Whether that beats investing depends on your rate, taxes, and risk tolerance, which the calculator does not model.
Is the first month's interest always the largest?
Yes for all three methods, unless you add an interest-only period, in which case interest stays flat until principal repayment starts.
Sources
- CFPB: What is the difference between a mortgage interest rate and an APR?
- CFPB: What is a prepayment penalty?
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About the results
Results depend on your inputs and assumptions. Check official sources or a qualified professional before using them for medical decisions, contracts or filings.