Home Loan Payment Calculator
This calculator compares standard monthly mortgage payments with two common bi‑weekly approaches: (A) bi‑weekly payments sized to amortize the loan over the same original term (26 payments per year); and (B) bi‑weekly payments equal to half the monthly payment (commonly used to accelerate payoff because it creates the equivalent of 13 monthly payments per year).
Use the fields below to enter your loan amount, APR, and term. Results show payment amounts, total paid, total interest, and estimated time to payoff for the half‑monthly bi‑weekly schedule. Results are estimates for planning only.
Governance
Record 552c660704c5 • Reviewed by Fidamen Standards Committee
Inputs
Results
Monthly payment
-$2.43
Bi‑weekly payment (26/yr, amortizes in same term)
-$0.52
Bi‑weekly payment (half of monthly payment every 2 weeks)
-$1.22
Number of monthly payments
360
Number of bi‑weekly periods (26/year)
780
Total paid (monthly schedule)
-$875.00
Total paid (bi‑weekly amortizes same term)
-$403.85
Estimated number of bi‑weekly payments (half of monthly payment schedule)
—
Total paid (bi‑weekly using half of monthly payment)
—
Total interest paid (monthly)
-$300,875.00
Total interest paid (bi‑weekly using half of monthly payment)
—
Interest savings vs monthly schedule (bi‑weekly half‑payment)
—
Estimated years to payoff (bi‑weekly using half of monthly payment)
—
Estimated years saved vs original term (bi‑weekly half‑payment)
—
| Output | Value | Unit |
|---|---|---|
| Monthly payment | -$2.43 | USD |
| Bi‑weekly payment (26/yr, amortizes in same term) | -$0.52 | USD |
| Bi‑weekly payment (half of monthly payment every 2 weeks) | -$1.22 | USD |
| Number of monthly payments | 360 | — |
| Number of bi‑weekly periods (26/year) | 780 | — |
| Total paid (monthly schedule) | -$875.00 | USD |
| Total paid (bi‑weekly amortizes same term) | -$403.85 | USD |
| Estimated number of bi‑weekly payments (half of monthly payment schedule) | — | — |
| Total paid (bi‑weekly using half of monthly payment) | — | USD |
| Total interest paid (monthly) | -$300,875.00 | USD |
| Total interest paid (bi‑weekly using half of monthly payment) | — | USD |
| Interest savings vs monthly schedule (bi‑weekly half‑payment) | — | USD |
| Estimated years to payoff (bi‑weekly using half of monthly payment) | — | years |
| Estimated years saved vs original term (bi‑weekly half‑payment) | — | years |
Visualization
Methodology
Calculations use standard annuity (level‑payment) amortization formulas. The periodic payment for a schedule with period rate r and N periods is: payment = (r * principal) / (1 - (1 + r)^(-N)).
For monthly results r = APR/12 and N = years*12. For bi‑weekly amortization r = APR/26 and N = years*26. For the common acceleration method (half the monthly payment every two weeks) we compute the number of bi‑weekly periods required to amortize with that fixed payment using the inverse of the annuity formula: N = -ln(1 - r*principal/payment) / ln(1+r).
Key takeaways
This tool provides comparative estimates between monthly payments and two bi‑weekly approaches. Use the half‑monthly bi‑weekly method to estimate accelerated payoff and interest savings.
For contractually accurate numbers, request an amortization schedule from your lender and review interest application rules, compounding conventions, and any fees or penalties.
F.A.Q.
Why do some bi‑weekly plans pay off faster?
If you pay half the monthly payment every two weeks you make 26 half‑payments per year, which equals 13 full monthly payments per year. That extra annual payment accelerates principal reduction and shortens the loan term.
Is the APR divided by 26 always correct for bi‑weekly?
This calculator assumes periodic interest = APR/26 (nominal APR divided by periods per year). Actual lenders may use different compounding conventions; always confirm the lender's interest compounding and payment application rules.
Should I round payment amounts?
Payments are typically rounded to cents by lenders. Small rounding differences can change the final payment or last payment slightly; for planning use unrounded values and expect minor differences in a real loan schedule.
How accurate are the results?
Results are estimates. They assume fixed APR, no fees, and that each payment is applied immediately to interest then principal. They do not model escrow, fees, prepayment penalties, interest rate changes, or payment timing irregularities.
What if my lender requires a different bi‑weekly schedule?
If the lender applies payments on specific dates, calculates interest using actual/365 or other day-counts, or charges processing fees, the real amortization will differ. Use lender-provided amortization schedules for exact figures.
Sources & citations
- Amortization basics (formula reference) — https://en.wikipedia.org/wiki/Loan_amortization
- NIST guidance on testing and validation of calculation software — https://www.nist.gov/publications
- ISO principles for financial services and risk management — https://www.iso.org/standards.html
- IEEE standards and best practices for numerical computing and software accuracy — https://standards.ieee.org/
- OSHA guidance (workplace safety standards referenced for operational controls in disclosure processes) — https://www.osha.gov/
- CFPB Regulation Z — 12 CFR § 1026.22 Determination of Annual Percentage Rate — https://www.consumerfinance.gov/rules-policy/regulations/1026/22/
- CFPB Appendix J — Annual Percentage Rate Computations for Closed-End Credit — https://www.consumerfinance.gov/rules-policy/regulations/1026/j/
- CFPB Annual Percentage Rate Tables — https://www.consumerfinance.gov/compliance/compliance-resources/other-applicable-requirements/annual-percentage-rate-tables/
Further resources
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: 552c660704c5What changed (latest)
v1.0.0 • 2025-11-04 • 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
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
What changed (latest)
v1.0.0 • 2025-11-04 • 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 4, 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 • 2025-11-04 • 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: a89c48cb1044
- https://en.wikipedia.org/wiki/Loan_amortization
- https://standards.ieee.org/
- https://www.consumerfinance.gov/compliance/compliance-resources/other-applicable-requirements/annual-percentage-rate-tables/
- https://www.consumerfinance.gov/rules-policy/regulations/1026/22/
- https://www.consumerfinance.gov/rules-policy/regulations/1026/j/
- https://www.iso.org/standards.html
- https://www.nist.gov/publications
- https://www.osha.gov/