BRRRR Calculator (Buy Rehab Rent Refinance)
This BRRRR calculator provides multiple underwriting views: a detailed monthly NOI and refinance view, a quick screening snapshot, and a refinance payment and coverage analysis. Use the detailed mode for due diligence and the quick snapshot for initial deal triage.
Results are modelled from user inputs and simplified amortization formulae where noted. Default values are conservative; replace with actual quotes from contractors, lenders, and tax authorities before final underwriting.
Governance
Record 65e2773c272c • Reviewed by Fidamen Standards Committee
Full-scope monthly and refinance view including invested capital, NOI, pre-refinance cash flow, refinance proceeds (approximate), cap rate and cash-on-cash return.
Inputs
Results
Total cash invested
$175,000.00
Monthly NOI
$939.00
Monthly cash flow (pre-refinance)
$939.00
Cap rate (%)
751.20%
Refinance loan amount
$165,000.00
Estimated cash out
$161,175.00
Net cash after refinance
-$13,825.00
Cash-on-Cash (%)
-790.00%
| Output | Value | Unit |
|---|---|---|
| Total cash invested | $175,000.00 | USD |
| Monthly NOI | $939.00 | USD |
| Monthly cash flow (pre-refinance) | $939.00 | USD |
| Cap rate (%) | 751.20% | % |
| Refinance loan amount | $165,000.00 | USD |
| Estimated cash out | $161,175.00 | USD |
| Net cash after refinance | -$13,825.00 | USD |
| Cash-on-Cash (%) | -790.00% | % |
Visualization
Methodology
Calculations separate operating performance (NOI) from financing effects. NOI is computed monthly as effective gross income (rent adjusted for vacancy) minus recurring operating expenses (taxes, insurance, management, maintenance, and other).
Refinance proceeds are estimated from ARV multiplied by a target LTV, minus existing loan balance and estimated refinance closing costs. Monthly amortizing payment on the new loan uses the standard fixed-rate annuity formula. Some refinance metrics are approximations; see accuracy caveats below.
Design and data handling follow established quality and security guidelines: test vectors and numeric stability checks are informed by IEEE numerical recommendations; handling of persisted or transmitted inputs should follow NIST best practices for data protection. Results are intended for underwriting support, not as an official loan commitment. For organizational processes consider ISO quality management principles.
Key takeaways
This calculator is a multi‑method BRRRR underwriting tool suitable for deal screening and initial due diligence. It provides both pre-refinance cash flow estimates and refinance cash-out approximations.
Inputs should be validated with contractor bids, property tax records, insurance quotes, and lender term sheets. Use outputs as a conservative baseline and document any assumptions used in pro forma analyses.
Worked examples
Example 1: Purchase $150k, rehab $20k, ARV $220k, target refinance LTV 75%; refinance loan is approximately $165k; cash-out equals $165k minus current balance and costs.
Example 2: If Monthly NOI is $600 and current mortgage payment is $400, pre-refinance cash flow is $200 per month. If refinance yields net cash greater than total invested, the deal is potentially cash-amplifying.
F.A.Q.
How accurate are the refinance and cash-out numbers?
Refinance and cash-out are estimates based on LTV, stated ARV, and user-entered fees. Actual lender eligibility, loan seasoning, title encumbrances, taxes, and market valuations change outcomes. Treat results as estimates and obtain lender quotes for firm numbers.
Does the calculator include taxes on cash-out or closing escrow requirements?
No. This tool does not calculate tax liabilities or escrow reserves. Consult a tax advisor and closing fee schedule; include those items in Other upfront costs if needed.
Why do some outputs use simplified payment formulas?
Monthly payment uses the fixed-rate annuity formula which assumes a fully amortizing loan at the stated rate. Interest-only products, adjustable rates, points that alter APR, and lender-specific fees are not modelled unless entered explicitly and may materially change payments.
What standards inform this tool's reliability and data handling?
Numeric stability and formula correctness align with IEEE guidance for numerical computations. For data protection and handling of user inputs, follow NIST recommendations. Organizational quality practices can follow ISO quality management principles. Site operators should follow applicable occupational safety guidance when performing on-site rehab work (OSHA).
Is this a substitute for lender underwriting or professional advice?
No. This calculator is a decision-support tool only. It is not a loan approval or tax, legal, or investment advice. Always confirm with lenders, contractors, and licensed professionals.
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
- HUD — FHA Single Family Housing Policy Handbook 4000.1 — https://www.hud.gov/program_offices/housing/sfh/handbook_4000-1
- HUD — Property Valuation and Appraisals (HUD 4155.2) — https://www.hud.gov/sites/documents/4155-2_4.pdf
- Fannie Mae — Selling Guide — https://selling-guide.fanniemae.com/
Further resources
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: 65e2773c272cWhat changed (latest)
v1.0.0 • 2025-11-18 • 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 • 2025-11-18 • 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 18, 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 • 2025-11-18 • 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: bb991cd6f91e