Cernarus

Home Loan APR Calculator with Bi-Weekly Payments

This calculator estimates your periodic payment, total interest paid, effective annual rate (EAR), and an approximate payoff time when making bi‑weekly or other frequent payments or adding an extra amount each period. It is intended for planning and comparison, not as a formal loan disclosure.

The tool converts a nominal APR into per‑period rates based on the selected payment frequency (for bi‑weekly use 26). It shows how extra periodic contributions affect total interest and the estimated time to pay off the loan.

Updated Nov 3, 2025

Inputs

Results

Updates as you type

Payment per period (includes extra payment)

$660.73

Scheduled number of payments

780

Total paid over life of loan (estimated)

$515,369.52

Total interest paid (estimated)

$215,369.52

Effective annual rate (EAR)

407.79%

Estimated payoff time (years) with extra payments

30

OutputValueUnit
Payment per period (includes extra payment)$660.73currency
Scheduled number of payments780—
Total paid over life of loan (estimated)$515,369.52currency
Total interest paid (estimated)$215,369.52currency
Effective annual rate (EAR)407.79%%
Estimated payoff time (years) with extra payments30—
Primary result$660.73

Visualization

Methodology

The calculator treats the loan as a fixed-rate amortizing loan. It derives the periodic payment from the annuity formula: A = r*P / (1 - (1+r)^-n), where r is the periodic interest rate and n is the total number of payments. If r is zero, payments equal principal divided by the number of periods.

Effective annual rate (EAR) is computed from the periodic rate as (1 + r)^(m) - 1, where m is the payment frequency per year. Estimates assume payments apply immediately to principal and interest according to the standard amortization schedule.

Calculation integrity and numeric stability follow general best practices for financial computations. For implementation and testing, follow IEEE floating point recommendations for numerical accuracy and, where required, align with ISO currency handling and NIST guidance on computational reproducibility.

Further resources

Expert Q&A

Is this an official APR disclosure from my lender?

No. This calculator provides estimates for planning and comparison only. Lenders must provide an official Truth-in-Lending disclosure (or equivalent) that states the legal APR. Use this tool to explore scenarios but rely on lender documents for legal terms.

Why do bi‑weekly payments often reduce total interest?

With bi‑weekly payments (26 per year) you make the equivalent of 13 monthly payments in a year rather than 12. By increasing the payment frequency and/or making extra periodic contributions, you reduce principal earlier, which lowers the total interest over the life of the loan.

How accurate are the payoff time and savings estimates?

Estimates assume on‑time payments, no fees, no escrow adjustments, and that extra payments go directly to principal. Results are sensitive to rounding, compounding conventions, and how a lender applies partial payments. Consider small rounding differences and consult your lender for exact payoff figures.

What should I consider before moving to bi‑weekly payments?

Confirm with your lender whether they support bi‑weekly schedules, how they apply payments to principal and interest, and whether fees apply. Some services collect funds and issue a single monthly payment; the timing of principal reduction affects savings.

Which standards were used to guide the calculator design?

Design and numeric recommendations reference recognized standards bodies for computational integrity and financial data handling. See citations for general guidance from NIST, ISO, and IEEE.

Sources & citations