Personal Loan Amortization Calculator
This amortization engine models personal loan repayment under multiple schedules: standard bi‑weekly (26 equal payments per year), accelerated bi‑weekly (half of the monthly payment applied every two weeks), and a monthly baseline for comparison. Enter principal, APR, term, and any constant extra payment to see periodic payment, total paid, total interest and estimated payoff time.
Results are calculated from standard amortization formulas. The calculator provides estimates for planning and comparison; actual lender schedules, rounding rules, payment application order, and fees can change outcomes.
Calculates a fixed periodic payment using 26 payments per year. Supports an optional constant extra payment applied to each bi‑weekly installment.
Inputs
Results
Bi‑weekly payment
-$0.33
Total paid over life of loan
-$43.27
Total interest paid
-$15,043.27
Payoff time (years)
5
Number of payments
130
| Output | Value | Unit |
|---|---|---|
| Bi‑weekly payment | -$0.33 | currency |
| Total paid over life of loan | -$43.27 | currency |
| Total interest paid | -$15,043.27 | currency |
| Payoff time (years) | 5 | years |
| Number of payments | 130 | payments |
Visualization
Methodology
We use discrete periodic compounding consistent with the selected payment frequency. The primary formulas derive the periodic interest rate as APR/periods-per-year and solve the annuity payment equation to compute required payment or number of periods.
For accelerated bi‑weekly, we compute the monthly payment first (12 periods/year), then set the bi‑weekly payment equal to half that monthly payment and solve for the number of bi‑weekly periods required to amortize the principal at the bi‑weekly periodic rate. This reflects the common accelerated bi‑weekly practice of creating an extra monthly payment over the year.
Worked examples
Example: $15,000 loan, 7.5% APR, 5 years — standard bi‑weekly payment is computed with 26 periods/year. Accelerated bi‑weekly equals half the monthly payment and typically reduces payoff time and interest by creating the effect of one extra monthly payment per year.
Add a constant extra payment per bi‑weekly installment to see direct reductions in payoff time and interest across all methods.
Further resources
Expert Q&A
What is the difference between standard and accelerated bi‑weekly?
Standard bi‑weekly uses 26 equal payments derived from the bi‑weekly annuity formula. Accelerated bi‑weekly sets the payment equal to half the monthly payment; because 26 half‑monthly payments equal 13 full monthly payments, this accelerates repayment and reduces interest.
Does this tool include fees or prepayment penalties?
No. This calculator does not include origination fees, late fees, prepayment penalties, or irregular payments. Enter additional fees as part of the loan principal or adjust results to account for penalties separately.
How accurate are the payoff estimates?
Estimates use standard mathematical models for amortization. Actual amortization may differ due to lender rounding rules, payment application order (principal vs interest), payment dates, and any account fees. See accuracy and standards citations below.
Can I model one‑time extra payments or varying extra payments?
This version supports a constant extra payment applied to each periodic installment. For one‑time or irregular extra payments, use an exportable amortization schedule and apply the extra payment at the appropriate date in a custom schedule tool.
Sources & citations
- NIST — Guidance on Calculator and Numerical Accuracy — https://www.nist.gov
- ISO — Numerical methods and computational accuracy guidance — https://www.iso.org
- IEEE — Floating‑point and numerical computation best practices — https://www.ieee.org
- OSHA — Not directly applicable to finance, cited for organizational standards practice — https://www.osha.gov