How this calculator works
Regular biweekly payments re-amortize the balance over 26 equal payment periods a year. Accelerated biweekly uses half the monthly payment every two weeks, giving thirteen monthly-payment equivalents each year. Accelerated weekly uses one quarter of the monthly amount each week. Add any extra amount to each alternative payment, not to each month. Both schedules assume one unchanged rate and no prepayment penalty.
Formula
i_f = (1 + r/c)^(c/f) - 1. Regular payment at frequency f = P × i_f / (1 - (1 + i_f)^(-Nf/12)). Accelerated biweekly = monthly payment / 2; accelerated weekly = monthly payment / 4. Each balance becomes balance × (1 + i_f) - actual payment.
Worked example
At 0%, $1,200 over twelve months requires $100 monthly. Accelerated biweekly pays $50 each time and clears the balance in 24 payments, or about 0.9231 years, rather than 26 regular biweekly payments.
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Frequently asked questions
Are biweekly and twice monthly the same?
No. Biweekly has 26 payments per year; twice monthly has 24. This calculator uses actual two-week spacing for displayed biweekly dates.
Where do the savings come from?
Acceleration adds annual principal payments. At 0% the time saving remains, but interest saved is zero.
Are dates exact?
Biweekly dates advance by fourteen days and weekly dates by seven. Interest uses equal periodic rates; lender daily accrual, holidays and rounding can change the statement.