Help Centre
Getting started, frequently asked questions and known limitations for Adjustmentstack.
Getting started
Adjustmentstack is a tool that shows you exactly which Fannie Mae loan-level price adjustments (LLPAs) affect a conventional mortgage price — and how they stack.
To use it: open the Calculator page, select your loan characteristics (FICO band, LTV/CLTV, purpose, occupancy, property type, loan amount band and lock period), and click "Calculate adjustments". The result is a ledger — each row names the published grid it came from, the exact cell that matched, and the adjustment amount. The total is the sum of every row.
No account, no login, no cost. Your scenario is not stored anywhere.
Frequently asked questions
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1. What does Adjustmentstack do?It applies Fannie Mae's published LLPA matrices to a set of loan characteristics and returns a stacked adjustment ledger — a line-by-line breakdown that shows every price adjustment, the grid it came from, and the exact cell that was matched. The output format is: "base 100.500; FICO 680–699 at 80.01–85% LTV −1.500; cash-out refinance −0.375; investment property −2.125; 60-day lock −0.250; = 96.250". Every number is checkable against the same published grid.
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2. Is this a rate quote, loan approval or offer of credit?No. The output is a price adjustment ledger for educational and analytical purposes. It is not a rate quote, a lock, a pre-approval or an offer of credit. Lenders set their own rates, margins and fees on top of the base price. Always verify the final rate with your loan officer or broker.
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3. Why does the calculator say "Under development"?The calculation API (the service that performs the grid look-up and arithmetic) is being built. Currently the calculator form shows your selected inputs in the ledger as a preview. The stacked adjustment rows with real values will appear once the API is deployed. See Known limitations below for the full status of every feature.
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4. Which grid data are you using?The calculator uses the Fannie Mae LLPA Matrix, effective 2024-07-01. The grids cover conventional conforming loans — base conforming, high-balance and super-conforming loan amounts. Grid data is captured as static tables and is not pulled live from a lender or investor feed. Published grids change periodically; always verify the current matrices on the Fannie Mae Single-Family website.
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5. What if my FICO or LTV is outside the grid?If any input falls outside the published grid boundaries (for example, a FICO below the lowest band or an LTV above the highest), the calculator will say "outside the published grid". It will not extrapolate, clamp silently to the nearest cell, or produce a confident wrong answer. No number is returned for a dimension that has no published match.
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6. Do you store my data? Do I need an account?No account, no login, no stored data. The calculator processes each scenario independently and returns the result to your browser. No loan characteristics, scenarios or results are retained on any server. There is no session tracking, no cookies and no user fingerprinting.
Known limitations
Calculation API not yet deployed
The /api/calculate service that performs grid look-ups and returns the
stacked ledger is written but not deployed. Until the site's worker is live, clicking
"Calculate adjustments" will display your inputs as a preview rather than real
adjustment values.
Only Fannie Mae conventional grids
Currently only Fannie Mae's conventional conforming LLPA matrix is loaded. Freddie Mac, jumbo loans, government loans (FHA, VA, USDA) and non-conforming products are not covered. No date has been set for expansion.
Static grid data — not live-refreshing
Grid tables are baked into the calculation code rather than pulled from a live feed. The effective date (2024-07-01) is stated on every result. When Fannie Mae publishes a new matrix, the grid data must be updated as a code change — there is no auto-update mechanism.
No scenario comparison, export or API access
Professional-tier features — side-by-side scenario comparison, CSV/text export of the ledger, and a public REST API — are described on the Pricing page but have not been built. No date has been set for any of them.
No email, alerts or subscriptions
This fleet has no email sender. The product cannot email you a result, notify you of grid changes, send a receipt, or send any kind of alert. No account system exists to store preferences for such notifications.
Contact us
How to reach support
A dedicated support email address has not yet been set up. Support is handled through this Help Centre page and the playbook documented internally.
In the meantime, if you have found an error in the calculator's arithmetic, a bug on the site, or a question not covered here, the issue will be reviewed when a contact channel is established. This limitation is tracked as an owner action.