- Payment frequency
- How often a payment is due: weekly (52 a year), bi-weekly (26), semi-monthly (24), monthly (12), quarterly (4) or annually (1). In this calculator every frequency repays the same loan over the same term at the same annual rate, so more frequent payments are simply smaller slices of a similar yearly total.
- Periodic interest rate
- The annual rate divided by the number of payments per year. At 7.5%, the monthly rate is 0.625% and the weekly rate is about 0.144%. This calculator uses this nominal periodic rate for each schedule, which is why total interest differs only slightly between frequencies when the term stays the same.
- Bi-weekly payment
- A payment every two weeks, 26 times a year. Here it is sized to repay the loan over the same term, so it is not the same as the common strategy of paying half the monthly amount every two weeks, which adds the equivalent of one extra monthly payment a year and pays the loan off early.
- Semi-monthly payment
- A payment twice a month, usually on fixed dates such as the 1st and 15th, for 24 payments a year. It is often confused with bi-weekly, which gives 26 payments. Each semi-monthly payment is close to half of the monthly payment, and the loan still ends on the same date.
- Principal
- The amount borrowed, or the part of the balance still owed, not counting interest. Each payment first covers interest due for the period; the rest reduces principal. Interest for the next period is charged only on the principal that remains, so paying principal down faster lowers total interest.
- Interest rate
- The annual percentage the lender charges on the unpaid balance, before fees. This calculator divides it by the number of payments per year to get the rate for each period, then applies that rate to the remaining principal, so a higher rate raises the payment at every frequency.
- Loan term
- The length of time scheduled to repay the loan in full. A longer term lowers each payment but keeps the balance outstanding longer, so total interest rises. In this calculator the term is held constant across all frequencies, which isolates the effect of payment timing.
- Amortization
- Paying down a loan through regular, equal payments that cover the interest due and reduce principal. Early payments are mostly interest; later ones are mostly principal. This calculator builds a separate amortization for each frequency, each ending at a zero balance on the same final date.
