Calculator
Example data table
| Type | # | Date | Payment | Interest | Principal | Balance |
|---|---|---|---|---|---|---|
| Grace | 0 | 2026-03-15 | $0.00 | $109.59 | $0.00 | $25,250.00 |
| Payment | 1 | 2026-09-15 | $270.41 | $110.49 | $159.92 | $25,090.08 |
| Payment | 2 | 2026-10-15 | $270.41 | $109.86 | $160.55 | $24,929.53 |
| Payment | 3 | 2026-11-15 | $320.41 | $108.88 | $211.53 | $24,718.00 |
| Payment | 4 | 2026-12-15 | $270.41 | $108.17 | $162.24 | $24,555.76 |
Formula used
For a fixed-rate loan, the scheduled payment is computed with the standard amortization formula: PMT = P × r ÷ (1 − (1 + r)−n) where P is the starting balance, r is the rate per period, and n is the number of scheduled payments.
Each period, interest accrues on the principal balance. Payments are applied to accrued interest first, then to principal. During grace/deferment, you can either pay nothing or pay interest only; unpaid interest can be capitalized (added to the balance) at the end of grace.
With the daily method, interest is estimated as Balance × APR ÷ 365 × Days between payment dates.
How to use this calculator
- Enter your loan amount, APR, and term length.
- Select a payment frequency and a start date.
- Add origination fees if your lender charges them.
- Set grace months and choose how to handle grace payments.
- Optionally add extra payments or a one-time lump sum.
- Press Calculate to see totals and the full schedule.
- Use Download CSV or Download PDF for records.
Payment drivers
Your scheduled payment is mainly set by balance, APR, and term. For example, a $25,000 balance at 5.25% APR over 10 years is about $270 per month. Shortening the term increases the payment but reduces total interest because principal falls faster. Switching frequency changes the per-period rate and the number of payments per year, which alters timing and the interest path.
Grace and capitalization impacts
During grace or deferment, interest can still accrue. If you pay nothing for six months at 5.25%, interest adds roughly $650–$700 on a $25,000 balance, depending on day counts. Paying interest-only during grace keeps the principal from growing. If unpaid interest is capitalized, it becomes principal, so future interest is charged on a higher balance and the payment may rise when repayment begins.
Extra payments and payoff acceleration
Extra payments target principal after interest for the period is satisfied. Even a $50 extra per period can cut several payments and save interest on a 10‑year loan, because each extra dollar reduces all future interest calculations. A one‑time lump sum, such as applying $1,000 at payment 12, creates an immediate drop in balance and can shorten the schedule more than spreading the same amount late in the term.
Fees and true borrowing cost
Origination fees change what you owe versus what you receive. A 1% fee on $25,000 is $250. If it is added to the balance, you repay interest on that $250 for the life of the loan. If paid upfront, your payment is lower, but your out‑of‑pocket cost is higher at disbursement. The calculator shows both approaches so you can compare total paid.
Interpreting the amortization schedule
Early payments are interest‑heavy because the balance is highest. Over time, interest declines and principal paid per period increases. Use the balance line and cumulative interest line to see when the loan “turns the corner.” If the term extends, it usually indicates unpaid accrued interest or too-small payments; capitalization or higher extras typically fixes it.
FAQs
Why does my payment change when I switch frequency?
Frequency changes how many payments you make each year and the rate per period. More frequent payments usually mean smaller per‑payment amounts, different interest timing, and sometimes a faster payoff when you keep the overall annual payment level similar.
What does it mean to capitalize interest after grace?
Capitalization adds unpaid accrued interest to the principal balance. Your new balance is higher, so future interest is calculated on that larger amount, and the recalculated payment can increase.
How do extra payments reduce total interest?
Extra dollars are applied to principal after interest for the period is covered. A lower principal balance reduces every future interest calculation, which can shorten the schedule and lower total interest paid.
Why can the term extend beyond the years I entered?
If accrued interest remains unpaid, or the effective payment is too small to cover interest plus principal reduction, the balance falls slowly. The calculator may extend payments until both principal and accrued interest reach zero.
Which interest method should I pick?
Choose Daily simple (365) when your lender accrues interest daily between payment dates. Per‑period is useful for simplified estimates. If you are unsure, run both and compare how sensitive your totals are to the method.
Can I export the full schedule for budgeting?
Yes. Use the Download CSV button for spreadsheets and the Download PDF button for a printable record. Exports reflect your exact inputs, including grace settings, fees, extra payments, and any lump sum.