75-101 Federal St
75-101 Federal St is a 21-story building in Downtown Boston with 89% of its floor area within daylight reach of a facade. This screen estimates 257 homes and scores it 96 out of 100 for office-to-residential conversion suitability.
MA-7 & MA-8 · Screened 2026-10-04 · Strong candidate
Where 75-101 Federal St is
Its block in Downtown Boston, drawn from Boston's own building outlines and street centerlines.
- Already housing
- Not screened
- 75-101 Federal St
This building's conversion pencils at default assumptions without any subsidy.
Across its 20 residential floors this building carries 30,353 sq ft of windowless core — area that must be gutted, re-plumbed and sprinklered but can never be rented as an apartment.
Modeled conversion metrics for 75-101 Federal St, 2026-10-04.
| Suitability scoreStrong candidate | 96 / 100 |
|---|---|
| Storiesfrom 248 ft aerial-survey height ÷ 12 ft floor-to-floor | 21 |
| Height bandsfloor plate by floor range, from the city's roof outlines | Floors 1–11: 18,464 sq ft · Floors 12–15: 16,399 sq ft · Floors 16–19: 4,092 sq ft · Floors 20–21: 2,497 sq ft |
| Floor platetypical floor, from the city outlines | 18,464 sq ft |
| Daylight efficiencyshare within 35 ft of a facade | 89% |
| Deepest interior pointviability threshold is 80 ft | 45 ft |
| Windowless coretypical floor; the building-wide total is in the text above | 2,432 sq ft |
| Estimated homesat 750 sq ft average | 257 |
| Conversion cost$360/sq ft all-in on 271,598 sq ft | $97.8M |
| Gap before grantpencils unsubsidized | -$15.7M |
| Modeled RESIDE grantat the statutory per-award cap | $10.0M |
| BuiltBoston's own record of the construction year | 1925 |
| ZoningDowntown Boston | SKY |
| Opportunity Zonenot in a 2018 designated tract | No |
The plan: window line, shape and floor rhythm
41 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.
The typical floor has 616 ft of exterior wall, and across 20 residential floors the building carries 10,463 ft of it in total, divided among the 257 homes this screen estimates.
Its plate is moderately compact at 0.61: a squarish plan, with enough perimeter for a conventional double-loaded corridor. How window line and plate shape are measured.
At the model’s 750 sq ft average, the plan works out at about 12.8 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.
Why 75-101 Federal St scores 96 out of 100
Daylight efficiency 98, Interior depth 87, Scale 100, Finance 100 — each out of 100, then weighted.
Score components for 75-101 Federal St. Points are the subscore times its weight.
| Component | Subscore | Weight | Points |
|---|---|---|---|
| Daylight efficiency89% of the floor area within 35 ft of a facade, scored from 40% up to 90% | 98 | 45% | 43.9 |
| Interior depthdeepest interior point 45 ft from a facade, scored from 80 ft down to 40 ft | 87 | 25% | 21.8 |
| Scale257 estimated homes, scored from 0 up to 150 | 100 | 15% | 15.0 |
| Financecompleted value covers conversion cost with 26% to spare, which tops out the component | 100 | 15% | 15.0 |
Most of what it earns comes from daylight efficiency, and what holds it back most is interior depth, at 87 out of 100: deepest interior point 45 ft from a facade, scored from 80 ft down to 40 ft.
Built in 1925
Boston records this building as going up in 1925, which puts it in the interwar stock.
As a rule, steel or concrete frames with punched windows and plates still narrow enough for daylight to reach the middle, often with high ceilings. Among the most convertible stock there is, and the reason so many early conversions were of buildings this age. That is the era’s general tendency rather than a finding about this building — the model reads an outline and a height, and can see nothing inside — but it is the first thing an architect would want to know, and it colours how much confidence the 89% daylight figure above deserves.
What the conversion would cost
$360 per square foot all-in across 271,598 sq ft of converted floor, or $97.8M in total — about $380K for each of the 257 homes.
All-in cost per square foot for 75-101 Federal St: base cost plus the code work a change of use triggers.
| Base conversion cost | $260/sq ft |
|---|---|
| Plumbing risers to every unit | $40/sq ft |
| Operable windows and glazing | $30/sq ft |
| Additional egress stair | $18/sq ft |
| Fire sprinklers (NFPA 13R) | $12/sq ft |
| All-in | $360/sq ft |
That cost is charged across every converted square foot, including the 30,353 sq ft of windowless core, which has to be gutted, re-plumbed and sprinklered like the rest of the building and then earns nothing. Against it the model sets a completed value of $442K a home, which for 257 homes is $113.5M.
What would have to be true
This one already clears the bar. The question is how much room it has before it stops.
At $442K a home, completed value covers the $97.8M of work with $15.7M to spare. Value per home would have to fall to $380K — 14% below the assumption — before the conversion stopped penciling, or all-in cost would have to rise from $360 to $418 per square foot. Neither is a wide margin in a market that moves, but this building does not need a grant to work.
Each of these, moved on its own, would be enough to undo that for 75-101 Federal St:
Single-assumption flip points for 75-101 Federal St, each holding the other three at their defaults.
| Completed value per homethe binding constraint — the least this building would need | 23% downto $342K |
|---|---|
| Circulation efficiency | 23% downto 62% |
| Average unit size | 29% upto 970 sq ft |
| Conversion cost per square foot | 36% upto $355/sq ft |
All four are sliders in the survey, where 75-101 Federal St re-scores against your own numbers.
How it compares in Downtown Boston
75-101 Federal St ranks 13th of the 96 buildings screened here, against a median score of 89.
Its floor plate is better lit than 49% of them, and shallower than 60% of them at its deepest interior point. On size it is the 39th largest by estimated homes. The full survey of all 96 buildings ranks and maps every one of them, and the list by address links each to its own page.
Within the SKY zone
7th of 52 zoned SKY — the comparison that shares its rules, rents and streets.
52 of the screened buildings are zoned SKY. 75-101 Federal St ranks 7th of them against a median score of 88. 40 score 70 or more, their median deepest interior point is 51 ft from a facade against this building’s 45 ft, and together they would hold an estimated 19,019 homes. The group’s top scorer is 147 Milk St, at 100.
Its nearest match in size: 175 Federal St
The screened building closest to 75-101 Federal St in converted floor area is 175 Federal St: 262,123 sq ft over 20 stories, against 271,598 sq ft over 21 here.
75-101 Federal St scores 96 to its 87, and with the size held roughly equal most of that lead comes from daylight efficiency: 98 out of 100 here, 86 there (83% of the floor area within 35 ft of a facade, scored from 40% up to 90%). On the money they sit in the same place: each pencils without a subsidy. The two stand about 700 ft apart.
Would it qualify for a RESIDE Act grant?
The model awards 75-101 Federal St $10.0M, on the assumption it qualifies. Whether it does, no published dataset can say.
That figure assumes the building meets the Act’s vacant-and-abandoned test, which turns on code-enforcement and receivership records no city publishes.
It does not sit in a 2018 designated Opportunity Zone, so it would not draw that Section 201 priority.
Other buildings screened near 75-101 Federal St
The 4 closest the screen also covers, from 110 ft away. They are the colored outlines on the plan at the top of this page.
- 101 Federal St31 stories · 91% daylit · 569 estimated homes · scores 93/100 (Strong candidate)about 110 ft away
- 20 Winthrop Sq6 stories · 100% daylit · 36 estimated homes · scores 89/100 (Strong candidate)about 200 ft away
- 70 Federal St9 stories · 100% daylit · 60 estimated homes · scores 91/100 (Strong candidate)about 260 ft away
- 100 Federal St50 stories · 62% daylit · 1,164 estimated homes · scores 35/100 (Marginal)about 280 ft away
A screen, not a feasibility study, from outlines and heights rather than plans: the method and how to correct a figure. If you know this building’s interior, you know what this model cannot see.