Fidamen

Home Loan Refinance Calculator with Bi-Weekly Payments

This calculator helps you evaluate switching to bi‑weekly payments either by refinancing into a bi‑weekly loan or by converting your existing mortgage schedule to bi‑weekly payments. It estimates periodic payments, total paid over the life of the loan, interest paid, and net savings after closing costs.

Results are estimates for planning purposes only. Inputs must be reviewed with your lender; real loan offers can differ due to fees, rounding, payment timing, local regulations, and credit underwriting.

Updated Nov 12, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record 1db449f47e46 • Reviewed by Fidamen Standards Committee

Refinance your current mortgage at a new rate/term and make bi‑weekly payments. Optionally roll closing costs into the new loan amount.

Inputs

Results

Updates as you type

Refinanced loan amount

$300,000.00

Bi‑weekly payment (refinance)

-$0.52

Total interest paid (refinance)

-$300,403.85

Total amount paid (refinance)

-$403.85

Current periodic payment

-$0.80

Total remaining under current schedule

-$519.23

Estimated net savings (one‑time closing costs considered)

-$115.38

Difference in years until payoff (current − refinance)

-5

OutputValueUnit
Refinanced loan amount$300,000.00USD
Bi‑weekly payment (refinance)-$0.52USD
Total interest paid (refinance)-$300,403.85USD
Total amount paid (refinance)-$403.85USD
Current periodic payment-$0.80USD
Total remaining under current schedule-$519.23USD
Estimated net savings (one‑time closing costs considered)-$115.38USD
Difference in years until payoff (current − refinance)-5years
Primary result$300,000.00

Visualization

Methodology

We model each scenario using standard amortizing loan formulas. For any schedule with payments per year m and nominal APR r, the periodic rate is r/m and the periodic payment solves P = A * r_periodic / (1 - (1 + r_periodic)^(-n)), where n is the total number of remaining periodic payments.

When comparing scenarios we compute the total amount paid over the relevant schedule (periodic payment × number of payments) and subtract principal to estimate total interest. Net savings subtract upfront closing costs if you choose not to roll them into the loan.

Worked examples

Example 1: $300,000 balance, 4.5% APR, 25 years remaining. Converting to bi‑weekly at same APR reduces interest slightly and may shorten payoff by a few years depending on schedule.

Example 2: Refinancing to 3.5% APR for 30 years and switching to bi‑weekly could lower periodic payments and reduce long‑term interest compared to staying at a higher rate, but include closing costs when assessing net benefit.

F.A.Q.

Why does switching to bi‑weekly payments save interest?

Bi‑weekly schedules make more frequent payments (26 vs 12) which reduces average outstanding principal faster. This reduces interest accrual between payments and can shorten total payoff time.

Does this calculator include taxes and insurance?

No. This tool models principal and interest only. Escrowed taxes, insurance, PMI, and lender fees are outside this calculation unless entered as closing costs.

Should I roll closing costs into the new loan?

Rolling closing costs increases the financed amount and will increase the interest you pay over time. Paying closing costs upfront reduces financed amount and may increase short‑term cost but lower long‑term interest. The calculator shows both effects depending on your selection.

How accurate are these estimates?

Estimates are mathematically precise for the amortization model used but depend on accurate inputs. Actual loan offers can vary due to payment timing, lender rounding, compounding conventions, prepayment penalties, or changes in rate. See accuracy caveats and disclaimers below.

What if my lender charges a fee to setup bi‑weekly payments?

Include any setup or administrative fees in the 'closing costs' input if they are paid upfront, or account for them in decision‑making if charged separately.

Sources & citations

Further resources

External guidance

Versioning & Change Control

Audit record (versions, QA runs, reviewer sign-off, and evidence).

Record ID: 1db449f47e46

What changed (latest)

v1.0.0 • 2025-11-12 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Public QA status

PASS — golden 25 + edge 120

Last run: 2026-01-23 • Run: golden-edge-2026-01-23

Engine

v1.0.0

Data

Baseline (no external datasets)

Content

v1.0.0

UI

v1.0.0

Governance

Last updated: Nov 12, 2025

Reviewed by: Fidamen Standards Committee (Review board)

Credentials: Internal QA

Risk level: low

Reviewer profile (entity)

Fidamen Standards Committee

Review board

Internal QA

Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person

Semantic versioning

  • MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
  • MINOR: New features or fields that do not change existing outputs for the same inputs.
  • PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.

Review protocol

  • Verify formulas and unit definitions against primary standards or datasets.
  • Run golden-case regression suite and edge-case suite.
  • Record reviewer sign-off with credentials and scope.
  • Document assumptions, limitations, and jurisdiction applicability.

Assumptions & limitations

  • Uses exact unit definitions from the Fidamen conversion library.
  • Internal calculations use double precision; display rounding follows the unit's configured decimal places.
  • Not a substitute for calibrated instruments in regulated contexts.
  • Jurisdiction-specific rules may require official guidance.

Change log

v1.0.0 • 2025-11-12 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 730b447e0c90