425 Harbor Dr
Key Biscayne, FL 33149 · single_family · For Sale · 82 days on market
Asking price$7,450,000
7 beds 9 baths 4,565 sqft
Listed by Mark Chatburn · One Sotheby's International Realty
Typesingle_family
Built2020
Price / sqft$1632
Est. value (own analysis)$9,890,226
Rent estimate (Zillow ZIP avg)$7,910/mo
HOANone
1 / 51
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Statusfor_sale
Listed date2026-06-12
Removed date—
MLSMiamiMLS #A12034564
Coordinates25.69340, -80.17203
Address425 Harbor Dr
CityKey Biscayne
StateFL
Zip33149
Listing ID5184497237
Sourceus-real-estate-listings, cached 2026-08-31
ZIP market snapshot (33149)
Typical home value (ZHVI)$1,692,135
Typical rent (ZORI)$7,910/mo
Zillow Research's ZHVI (home value index) and ZORI (rent index) for this ZIP, as of 2026-07 — free published data, refreshed monthly, no RentCast quota spent. "Typical value/rent" is a smoothed index, not a literal median of active listings.
Underwriting (buy-and-hold, default assumptions)
| Acquisition (one-time, not monthly/yearly) | |
| Purchase price | $7,450,000 |
| Down payment (20.0%) | $1,490,000 |
| Loan amount | $5,960,000 |
| Closing costs (5.0%) | $372,500 |
| Total cash to close | $1,862,500 |
| Income | |
| Rent (ZIP avg, ZORI — not bedroom-specific) | $7,910$94,922 |
| Vacancy loss (8.0%) | |
| Effective gross income | $7,277$87,328 |
| Operating expenses | |
| Property tax (placeholder 1.9% of price) | $11,796$141,550 |
| Insurance (placeholder 0.8% of price) | $4,967$59,600 |
| HOA dues | $0$0 |
| Management (0.0% of EGI) | $0$0 |
| Maintenance (5.0% of GSR) | $396$4,746 |
| Total operating expenses | $17,158$205,896 |
| Net operating income (NOI) | |
| Debt service & reserves | |
| Debt service (6.66%, avg 30yr rate as of 2026-08-27, 30yr amortizing) | |
| CapEx reserve (5.0% of GSR) | $396$4,746 |
| Mortgage insurance (PMI) (0.0% of loan, not required — down payment ≥ 20%) | $0$0 |
| Cash flow |
Cap rate
Cash-on-cash
DSCR
Rent-to-price (1% rule)
Gross rent multiplier
Operating expense ratio
Break-even occupancy
Comparables
Same ZIP. Real active rental listings, used to derive the rent estimate above.
No active rental listings cached yet for this bedroom count.
Same ZIP & bedroom count. Closed sales from Realtor.com over the last 12 months, matched to this property's type — real transaction prices, not asking prices. Falls back to Miami-Dade County public records (property appraiser tax roll) when Realtor.com has no sales on file for the area.
| Address | Type | Beds | Baths | Living sqft | Sale price | Sale date |
|---|---|---|---|---|---|---|
| 111 Reef Ln | single_family | 7 | 6 | 5,008 | $10,850,000 | 2026-08-07 |
| 230 Harbor Dr | single_family | 7 | 8 | 6,240 | $17,500,000 | 2026-07-08 |
| 797 Ridgewood Rd | single_family | 7 | 8 | 5,528 | $6,500,000 | 2026-03-31 |
Same ZIP. Other properties currently for sale nearby — asking prices, not closed sale prices. Not a price comp; see Sold comps for actual transaction history.
| Address | Type | Beds | Baths | Sqft | Asking price | Days on market |
|---|---|---|---|---|---|---|
| 550 Harbor Dr | single_family | 7 | 8 | 6,497 | $19,450,000 | — |
10-year hold projection
IRR-10.9%
Equity multiple-0.87x
Total return (10yr)-$2,505,449
| Year | Property value | NOI | Cash flow | Loan balance | Equity |
|---|---|---|---|---|---|
| 1 | $7,673,500 | -$118,568 | -$582,921 | $5,895,380 | $1,778,120 |
| 2 | $7,903,705 | -$121,096 | -$585,567 | $5,826,323 | $2,077,382 |
| 3 | $8,140,816 | -$123,673 | -$588,267 | $5,752,524 | $2,388,293 |
| 4 | $8,385,041 | -$126,302 | -$591,020 | $5,673,656 | $2,711,384 |
| 5 | $8,636,592 | -$128,982 | -$593,828 | $5,589,373 | $3,047,219 |
| 6 | $8,895,690 | -$131,715 | -$596,692 | $5,499,302 | $3,396,388 |
| 7 | $9,162,560 | -$134,502 | -$599,613 | $5,403,046 | $3,759,515 |
| 8 | $9,437,437 | -$137,343 | -$602,592 | $5,300,179 | $4,137,258 |
| 9 | $9,720,560 | -$140,240 | -$605,629 | $5,190,249 | $4,530,311 |
| 10 | $10,012,177 | -$143,193 | -$608,727 | $5,072,770 | $4,939,407 |
Assumes 3.0% annual rent growth, 2.5% expense growth, 3.0% appreciation, and a 6.0% selling cost at exit — all placeholder assumptions, not market-derived.