Home Loan Interest Calculator
This calculator compares standard monthly amortization to bi‑weekly payment schedules for a home loan. Enter the loan amount, annual interest rate (APR), term in years, and any optional additional amount you plan to add to each bi‑weekly payment.
Results show the estimated monthly and bi‑weekly payment amounts, total interest paid under each schedule (using 26 bi‑weekly periods per year), estimated interest savings, total paid under a bi‑weekly schedule, and an approximate payoff time when making bi‑weekly payments including extras.
Inputs
Results
Estimated monthly payment (no extra)
$1,347.13
Estimated bi‑weekly payment (base + extra)
$621.48
Total interest paid with monthly payments
$184,968.26
Total interest paid with bi‑weekly payments (assumes 26 periods/year)
$184,753.30
Estimated interest saved (monthly − bi‑weekly)
$214.96
Total amount paid with bi‑weekly schedule
$484,753.30
Approximate payoff time with bi‑weekly payments (years)
—
| Output | Value | Unit |
|---|---|---|
| Estimated monthly payment (no extra) | $1,347.13 | USD |
| Estimated bi‑weekly payment (base + extra) | $621.48 | USD |
| Total interest paid with monthly payments | $184,968.26 | USD |
| Total interest paid with bi‑weekly payments (assumes 26 periods/year) | $184,753.30 | USD |
| Estimated interest saved (monthly − bi‑weekly) | $214.96 | USD |
| Total amount paid with bi‑weekly schedule | $484,753.30 | USD |
| Approximate payoff time with bi‑weekly payments (years) | — | years |
Visualization
Methodology
Calculations use standard amortization formulas converting the annual nominal rate to the period rate (monthly = annual/12, bi‑weekly = annual/26) and the standard annuity formula for level payments. For zero interest rate the calculator uses linear repayment to avoid division by zero.
This tool provides deterministic mathematical estimates for comparison and planning. It does not account for lender-specific policies (for example, whether your lender applies bi‑weekly payments as credited halves of a monthly payment, posts payments immediately, or applies payments toward principal on receipt). Use the results for planning and discuss exact payoff timing with your lender.
Further resources
Expert Q&A
Does a bi‑weekly schedule always save interest?
Generally yes when bi‑weekly payments result in an extra equivalent monthly payment each year or when additional per‑payment principal is applied. Savings depend on exact payment amount, timing, and how the lender posts payments.
Why do some calculators show different savings for the same inputs?
Differences come from modeling choices: whether bi‑weekly is treated as 26 equal payments per year, whether half‑monthly payments are used, how interest is compounded, and whether lender posting rules or prepayment penalties are modeled.
How accurate are these estimates?
Estimates use standard amortization mathematics but are approximate for real‑world payoff timing. They do not substitute for lender statements or escrow/tax/fee calculations. See accuracy caveats and standards references below.
Sources & citations
- National Institute of Standards and Technology (NIST) — https://www.nist.gov
- International Organization for Standardization (ISO) — https://www.iso.org
- Institute of Electrical and Electronics Engineers (IEEE) — https://www.ieee.org
- Occupational Safety and Health Administration (OSHA) — https://www.osha.gov