101 Mission St

101 Mission St is a 21-story building in Downtown San Francisco with 93% of its floor area within daylight reach of a facade. This screen estimates 220 homes and scores it 99 out of 100 for office-to-residential conversion suitability.

CA-11 · Screened 2026-10-12 · Strong candidate

Build a free conversion planCheck its numbers, lay out its homes and get a two-page PDF. Free.

Also addressed as 100 Spear St: San Francisco’s address records place both on this one footprint.

Where 101 Mission St is

Its block in Downtown San Francisco, drawn from San Francisco's own building outlines and street centerlines.

201 Spear St: scores 92 out of 100121 Steuart St: scores 89 out of 100131 Steuart St: scores 89 out of 10060 Spear St: scores 83 out of 100155 Main St: scores 81 out of 100150 Spear St: scores 79 out of 100120 Howard St: scores 72 out of 100180 Howard St: scores 67 out of 100101 Market St: scores 57 out of 1008381797299SPEAR STMISSION STMAIN STN100 ftDowntown San Francisco
Suitability score
0–29
30–49
50–69
70–100
  • Already housing
  • Not screened
  • 101 Mission St
101 Mission St and the 1,000 ft of Downtown San Francisco around it. The streets are drawn at the width of the right-of-way they run down, sidewalks included, and named, and every building on these blocks is drawn. What is left open and stippled is neither: a surface lot, a plaza or a vacant parcel. The screened buildings are colored by the ramp above, the same one the district map uses, carry their score, and each is a link to its own page. Each casts a shadow as long as its measured height lets it, so towers stand out from the low buildings around them; the unscreened buildings have no measured height and cast none. 101 Mission St is outlined in its own score color at the outline it covers at ground level. Its windowless core is hatched. The inset places it among every building the screen covers.
41 ftAA50 ftDaylit 93%Core 805 sq ft
Floor plan: 93% of each floor sits within daylight reach of a facade. The shading is daylight, darkest at the windows and gone 35 ft in. The hatched area is windowless core: 805 sq ft per floor that must be renovated but can never be rented as an apartment. The dimension marks the deepest interior point, 41 ft from the nearest window. A–A is where the section beside it is cut.
Windowless core21 floors50 ft
Section A–A: cut across the depth of the plate, through the middle of the core. Daylight reaches 35 ft in from every facade, fading as it goes, and the hatched stripe left between the lit edges is floor that gets converted and can never be rented: 805 sq ft on the floor the screen scores, and 16,103 sq ft over 20 residential floors. The shaded ground floor is converted like the rest and counted as no homes.

This building does not pencil on its own, but a modeled RESIDE Act grant would close the gap if the building qualified for one.

Every floor carries 805 sq ft of windowless core — area that must be gutted, seismically braced and sprinklered but can never be rented as an apartment. Across 20 residential floors that is 16,103 sq ft of cost carrying no revenue.

Modeled conversion metrics for 101 Mission St, 2026-10-12.

Suitability scoreStrong candidate99 / 100
Storiesfrom 284 ft LiDAR (2010) height ÷ 12 ft floor-to-floor21
Floor plateper floor, from the city footprint11,128 sq ft
Daylight efficiencyshare within 35 ft of a facade93%
Deepest interior pointviability threshold is 80 ft41 ft
Windowless coreper floor — renovated but never rentable805 sq ft
Estimated homesat 750 sq ft average220
Conversion cost$405/sq ft all-in on 222,557 sq ft$90.1M
Gap before grantshortfall against completed value$9.6M
Modeled RESIDE grantat the statutory per-award cap$10.0M
BuiltSan Francisco's own record of the construction year1985
ZoningFinancial District/South BeachC-3-O(SD)
Opportunity Zonenot in a 2018 designated tractNo

The plan: window line, shape and floor rhythm

40 ft of exterior wall for each home the screen estimates — enough for two- and three-bedroom homes across the plan.

The typical floor has 445 ft of exterior wall, and across 20 residential floors the building carries 8,891 ft of it in total, divided among the 220 homes this screen estimates.

Its plate is moderately compact at 0.71: 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 11.0 homes per floor, repeated on every residential floor, since this building's outline does not change as it rises.

Why 101 Mission St scores 99 out of 100

Daylight efficiency 100, Interior depth 97, Scale 100, Finance 100 — each out of 100, then weighted.

Score components for 101 Mission St. Points are the subscore times its weight.

ComponentSubscoreWeightPoints
Daylight efficiency93% of the floor area within 35 ft of a facade, scored from 40% up to 90%10045%45.0
Interior depthdeepest interior point 41 ft from a facade, scored from 80 ft down to 40 ft9725%24.1
Scale220 estimated homes, scored from 0 up to 15010015%15.0
Financecompleted value covers conversion cost with 0% to spare, which tops out the component10015%15.0

Every component scores at or near full marks, so nothing in the geometry or the pro-forma is holding this one back — daylight efficiency carries the most weight of the four.

Built in 1985

San Francisco records this building as going up in 1985, which puts it in the late-modern stock.

As a rule, typically the hardest to convert: the deepest plates of any era, large central cores, and floor-to-floor heights tight enough that running residential drainage under a ceiling can be the thing that ends a project. 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 93% daylight figure above deserves.

What the conversion would cost

$405 per square foot all-in across 222,557 sq ft of converted floor, or $90.1M in total — about $410K for each of the 220 homes.

All-in cost per square foot for 101 Mission St: base cost plus the code work a change of use triggers.

Base conversion cost$260/sq ft
Seismic retrofit (change of use)$45/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$405/sq ft

That cost is charged across every converted square foot, including the 16,103 sq ft of windowless core, which has to be gutted, seismically braced and sprinklered like the rest of the building and then earns nothing. Against it the model sets a completed value of $366K a home, which for 220 homes is $80.5M.

What would have to be true

A $9.6M gap before any grant, which the modeled $10.0M closes. What would reopen it soonest: completed value per home under 1% down.

The shortfall before any grant is $9.6M. Closing it from the value side means each of the 220 homes finishing at $410K rather than the $366K the model assumes — 12% more. Closing it from the cost side means getting all-in cost down from $405 to $362 per square foot.

A modeled RESIDE grant of $10.0M moves that threshold to $364K a home. That is below the assumed value, which is why this building counts as unlocked by the grant — subject to it qualifying under the law's vacant-and-abandoned test, which this data cannot show.

Each of these, moved on its own, would be enough to undo that for 101 Mission St:

Single-assumption flip points for 101 Mission St, each holding the other three at their defaults.

Completed value per homethe binding constraint — the least this building would needunder 1% downto $364K
Circulation efficiency1% downto 80%
Average unit size1% upto 754 sq ft
Conversion cost per square foot1% upto $262/sq ft

All four are sliders in the survey, where 101 Mission St re-scores against your own numbers.

How it compares in Downtown San Francisco

101 Mission St ranks 22nd of the 205 buildings screened here, against a median score of 87.

Its floor plate is better lit than 57% of them, and shallower than 59% of them at its deepest interior point. On size it is the 81st largest by estimated homes. The full survey of all 205 buildings ranks and maps every one of them, and the list by address links each to its own page.

Within Financial District/South Beach and the C-3-O(SD) zone

21st of 165 in Financial District/South Beach, 3rd of 66 zoned C-3-O(SD) — the comparison that shares its rules, rents and streets.

San Francisco places 165 of the screened buildings in Financial District/South Beach. 101 Mission St ranks 21st of them against a median score of 88. 121 score 70 or more, their median deepest interior point is 47 ft from a facade against this building’s 41 ft, and together they would hold an estimated 40,456 homes. The group’s top scorer is 870 Market St, at 100.

66 of the screened buildings are zoned C-3-O(SD). 101 Mission St ranks 3rd of them against a median score of 72. 37 score 70 or more, their median deepest interior point is 59 ft from a facade against this building’s 41 ft, and together they would hold an estimated 18,546 homes. The group’s top scorer is 140 New Montgomery St, at 100.

Its nearest match in size: 88 Kearny St

The screened building closest to 101 Mission St in converted floor area is 88 Kearny St: 221,903 sq ft over 21 stories, against 222,557 sq ft over 21 here.

The two land within a few points of each other — 99 here, 100 there — so at this size the screen reads them as much the same prospect. On the money they sit in the same place: each pencils only with the modeled RESIDE grant. The two stand about 3,000 ft apart.

Would it qualify for a RESIDE Act grant?

The model awards 101 Mission 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 101 Mission St

The 4 closest the screen also covers, from 190 ft away. They are the colored outlines on the plan at the top of this page.

  • 150 Spear St
    18 stories · 83% daylit · 234 estimated homes · scores 79/100 (Strong candidate)
    about 190 ft away
  • 60 Spear St
    12 stories · 84% daylit · 140 estimated homes · scores 83/100 (Strong candidate)
    about 210 ft away
  • 155 Main St
    19 stories · 83% daylit · 244 estimated homes · scores 81/100 (Strong candidate)
    about 320 ft away
  • 120 Howard St
    12 stories · 77% daylit · 171 estimated homes · scores 72/100 (Strong candidate)
    about 400 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.