Biweekly Loan Amortization Schedule Calculator

This biweekly loan amortization calculator estimates the payment made every two weeks, the payoff timeline, and total interest for a fixed-rate loan. Enter the loan amount, annual APR, and term; the results use 26 equal payments per year and show how that schedule differs from paying monthly.

Formula

The calculator treats the stated term as a fixed number of years and divides it into 26 equal payment periods per year. It calculates a level payment using the periodic rate and number of payments:

• Periodic rate, r = APR / 2600, where APR is the annual percentage rate entered as a percentage. This assumes the APR is divided by 26 for the biweekly calculation.
• Number of payments, n = years × 26.
• Biweekly payment, M = P × r / [1 − (1 + r)⁻ⁿ], rounded to the nearest cent.
• Total interest, I = M × n − P, where the rounded payment is used.

P is the starting principal in dollars, r is the rate per two-week period as a decimal, n is the number of payment periods, and M is the payment in dollars. The formula assumes each payment is the same and is made at the end of a period. Actual loan contracts can calculate interest and due dates differently.

Worked Example

Using the calculator’s default inputs—$20,000 principal, 8% APR, and a 5-year term:

1. Calculate the period rate: 8 / 2600 = 0.003076923, or about 0.3076923% per two weeks.
2. Calculate the payment count: 5 × 26 = 130 payments.
3. Apply the payment formula: $20,000 × 0.003076923 / [1 − (1 + 0.003076923)⁻¹³⁰] = about $188.65 per payment after cent rounding.
4. Calculate total interest using that rounded payment: $188.65 × 130 − $20,000 = $4,524.50.

The results describe the calculator’s stated convention, not necessarily the exact schedule a lender would issue.

Assumptions

• The interest rate remains fixed throughout the modeled term.
• Payments are equal and made at the end of each two-week period.
• Interest accrues using a periodic rate of APR divided by 26; the calculator does not model daily accrual or a lender’s specific compounding convention.
• There are 26 periods per year, so the modeled term contains years × 26 payments.
• Fees, taxes, insurance, PMI, escrow, late payments, and additional principal payments are not included.

How a Biweekly Schedule Works

A biweekly schedule has a payment every 14 days. Because 52 weeks contain 26 two-week periods, a year normally has 26 scheduled payments. This differs from paying twice a month: semimonthly payments occur on two chosen dates each month, giving 24 payments per year. The terms are not interchangeable.

When a borrower makes half of a monthly payment every two weeks, the yearly amount paid is commonly equivalent to 13 full monthly payments: 26 half-payments equal 13 monthly payments. That can reduce a balance sooner if the extra annual amount is actually applied to principal and the loan permits the payment arrangement. This calculator instead divides the loan into 26 equal biweekly installments over the original term. It does not model a half-monthly-payment service, its fees, or the lender’s treatment of funds received before a due date.

How to Read the Results

The first result is the estimated amount due each two weeks under the calculator’s fixed-rate assumptions. The total-interest figure is the sum of those rounded payments minus the initial principal. It is not the total amount paid; add principal to interest to get the modeled total of all payments.

For the example, 130 payments of $188.65 total $24,524.50, comprising $20,000 principal and $4,524.50 interest. Small differences can arise in a real account because the final payment may be adjusted, payment dates vary, or interest may accrue daily. The result should therefore be read as a mathematical estimate, not a lender-issued amortization schedule.

Using the Estimate and Common Pitfalls

Use the APR and original term shown in the lender’s loan documents or quote rather than a guessed rate. APR can reflect certain borrowing costs, while the loan’s interest-rate and payment calculations may follow separate contract terms. Ask the lender how it calculates interest, whether the payment is credited immediately, and whether extra amounts are applied to principal.

• Confusing biweekly with twice monthly: 26 biweekly payments and 24 semimonthly payments are different schedules.
• Assuming a half-payment automatically pays principal: A lender or payment processor may hold partial payments until a full installment is received. Confirm how payments are credited.
• Ignoring rounding: The calculator rounds each regular payment to cents and uses that rounded amount for total interest. A final installment may differ slightly.
• Entering the wrong term: The year input is the full modeled payoff term, not the number of years remaining unless that is what you intend to estimate.
• Leaving out charges: The result excludes fees and other costs unless they are included in the principal or represented elsewhere in the loan terms.

To create an account-level schedule, a borrower needs the lender’s payment dates, balance, rate basis, accrued-interest method, and rules for applying partial or extra payments. A standard amortization table then allocates each payment between interest and principal and updates the remaining balance. Since each payment changes the balance, the interest portion generally declines over time while the principal portion rises, assuming a fixed rate and regular payments.

Frequently Asked Questions

Does paying biweekly save interest?
It can lower interest when it results in principal being paid sooner or an extra annual payment being applied to principal. The effect depends on the contract’s interest calculation and payment-crediting rules; a biweekly label by itself does not guarantee savings.

Is biweekly the same as twice a month?
No. Biweekly means every 14 days, usually 26 payments in a year. Twice monthly means two payments each month, usually 24 annually, on dates set by the arrangement.

Does this calculator show a lender’s exact schedule?
No. It is a level-payment estimate using a fixed rate, APR divided by 26, and end-of-period payments. The lender’s schedule may use daily interest, different dates, fees, or a different final payment.

Can I use it for a variable-rate loan?
Only as a snapshot based on the rate entered. If the rate changes, future payments or the payoff timeline may change, so the displayed totals will not represent the full variable-rate loan.

Why is a biweekly payment not half the monthly payment?
A monthly payment and a biweekly payment cover different numbers of periods. A simple half-monthly payment is often used in payment plans, but this calculator independently amortizes the loan across 26 periods per year.

This result is an estimate; the lender’s disclosure gives the exact figures.

Related

• Journal Entry for a Long-Term Loan: Example and Guide
• Jane Street Term Loan B: What It Means
• JN Bank Term Share Loan: How It Works and Costs

in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Biweekly payment | $ | round(p * (apr / 2600) / (1 - (1 + apr / 2600) ^ -(yrs * 26)), 2) | 2
out int | Total interest | $ | pmt * yrs * 26 - p | 2