Method
How Stackup sizes a multifamily loan
Each program gets the same inputs and its own published limits. The app computes a loan by value, a loan by income, applies any dollar cap, and keeps the smallest. Here is every step, with the example building worked through.
The two tests
By value
Max loan = value × max LTV. For purchases, enter the lower of price and appraised value, since lenders use the lower. For construction under HUD 221(d)(4), the test runs on total development cost (loan-to-cost) instead.
By income
Max loan = NOI ÷ (min DSCR × annual loan constant). The annual loan constant is the yearly principal and interest on $1 of loan at the rate and amortization you chose. At 6.75% over 30 years it is 0.0778; over 35 years, 0.0746.
For HUD programs the app adds the 0.25% annual mortgage insurance premium to the constant, treating the premium as part of the yearly payment. That lowers HUD estimates a little. Your HUD lender's sizing may treat it differently.
Worked example
The made-up building on the home page: 48 units, $610,000 NOI, $9,400,000 value, refinancing, rate 6.75%.
| Step | Fannie Mae DUS | HUD 223(f) |
|---|---|---|
| Max LTV | 80% × value = $7,520,000 | 87% × value = $8,178,000 |
| Annual constant | 0.0778 (30 yrs) | 0.0746 + 0.0025 MIP (35 yrs) |
| Max by DSCR | $610,000 ÷ (1.25 × 0.0778) = $6,269,933 | $610,000 ÷ (1.15 × 0.0771) = $6,882,508 |
| Max loan | $6,269,933, DSCR binds | $6,882,508, DSCR binds |
Coverage binds on both. That is common when rates are where they are now: the appraisal could come in higher and neither loan would grow. Only more NOI, a lower rate or a longer amortization moves them.
The rate
One rate runs through every program so the comparison isolates the sizing rules. It is a U.S. Treasury par yield (you pick 5, 7 or 10 years) plus a spread you set. The default spread, 1.75%, is an example input. No agency publishes spreads, and real pricing differs between programs and between lenders, so treat the rate as a dial for sensitivity, not as a quote.
Treasury yields on : 5-year 4.82%, 7-year 4.89%, 10-year 5.00% (U.S. Treasury daily par yield curve). The build-time file was last refreshed October 24, 2026 by scripts/refresh_rates.sh. Between builds, the page and the app check the portfolio's rate feed, which reads the same Treasury curve every business day, and show a newer yield with its date when there is one.
Program rules the app applies
- Freddie Mac's grid is 75% LTV for terms under 7 years and 80% for 7 years and up. The app picks the shortest offered term that covers your hold period (5, 7 or 10 years for Optigo Conventional; 5, 7, 10, 12 or 15 for Conventional Small).
- Fannie Mae Small Loans stop at $9 million. Freddie Conventional Small runs from $2 million to $10 million and 5 to 50 units. Freddie's larger Optigo Conventional loans start at $10 million.
- HUD's tiers are 87% and 1.15x for market-rate deals, 90% and 1.11x for affordable deals with a rent advantage or 90%+ rental assistance (Mortgagee Letter 2025-03). For a 223(f) cash-out, the loan is also capped at the greater of 80% of value or the cost to refinance.
- HUD 223(a)(7) only refinances loans already FHA-insured, with no cash out. The app caps it at your current balance (HUD also allows permitted costs on top) and at 1.11x coverage (1.05x when over 90% of units have project-based Section 8). Amortization is your remaining term plus up to 12 years.
- Some rows aren't sized. Fannie Mae's affordable (MAH) term sheet isn't in the program book yet, so affordable deals show "other term sheet" on the Fannie DUS row. Bank, CMBS, bridge and DSCR loans have no published terms. SBA excludes apartment buildings.
What it can't see
Lenders re-underwrite NOI (often lower than yours), order their own appraisal, require reserves, and price the rate. Agency tiers inside Fannie Mae's Form 4660 and the details of each lender's credit box aren't public. An estimate here is a starting point for a conversation with a lender or broker, not a substitute for one.
Every limit, with its source and date, is on the program page.
Get an email when the 10-year moves
Agency fixed rates price off Treasuries, so a quarter point on the 10-year changes what your coverage test allows. On the example building, every 0.25% on the rate moves the Fannie Mae DSCR limit by roughly $163,974.
Live data, API and embeds
The yields on this page come from /api/live, a small JSON endpoint anyone can call. GET /api/live?ids=UST5,UST7,UST10,SOFR returns each series' latest value, its date, the reading a week and a month earlier, a freshness status and the publisher's link. Add &history=60 for 60 days of daily points. Treasury par yields are U.S. government data. SOFR comes from the Federal Reserve Bank of New York; its content is subject to the Terms of Use at newyorkfed.org, and this site is not affiliated with the New York Fed.
To show the same rates on your site, paste this:
<iframe src="https://multifamily.online/embed/rates?ids=UST5,UST7,UST10,SOFR" width="100%" height="150" style="border:0" title="Rates from Stackup" loading="lazy"></iframe>The comparison app itself can be framed too. The embed page has that snippet and what it does.
License: Treasury and New York Fed data stay under their publishers' terms. Stackup's compilation of program limits on the program page may be reused under CC BY 4.0 with the credit "Data: Stackup (multifamily.online)" and a link. No warranty. For bulk or commercial use, email hello@multifamily.online.