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    Key West Duplex Investment Opportunity Title is generated by Realmo AI

    1911 Seidenberg Avenue, Key West, FL 33040

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    For Sale
    $1,250,000

    Well-maintained duplex in Key West's Midtown East neighborhood.

    Type:Multi-Family
    Property size:
    1,119 SF
    Lot size:
    0.11 Acres
    Price / SF:
    $1,117/SF
    Added:
    Apr 29, 2026
    Days on Market:
    35
    Last Refresh:
    May 27 at 7:36 am

    Property Features for 1911 Seidenberg Avenue

    General Information

    Standard status
    Active
    Size
    1,119 SF
    Lot size
    0.11 Acres
    Property subtype
    Multi-Family

    Building Details

    Year Built
    1943

    We can help!

    Listing Contact
    Everett Smith

    Listing agent Everett Smith License #670558

    Listing office Ocean Sotheby's International Realty

    Listing date Apr 29, 2026

    Source Xome

    Displayed information is deemed reliable but is not guaranteed and should be independently verified.

    All listing content including descriptions, pricing, images are the copyrighted material of Ocean Sotheby's International Realty

    HighLights

    • Legal duplex featuring two separately metered 1‑bedroom, 1‑bath units.
    • Desirable Midtown East location, close to Key West attractions.
    • Updated with Mitsubishi mini‑split A/C, new hot water heater, impact windows upstairs, new gutters, and updated appliances.
    • Lush, mature tropical landscaping on a 5,000 sq ft lot.
    • Two off‑street parking spaces.
    • Enjoy indoor‑outdoor living with two large screened porches and additional open‑air spaces.

    Overview

    This well-maintained two-story property, with a history of only two owners, is a legal duplex featuring two separately metered 1-bedroom, 1-bath units. Situated on a 5,000 sq ft lot, the property is surrounded by mature tropical landscaping, creating a private, shaded setting with natural light. The property offers flexibility for investors seeking rental potential, business owners needing employee housing, or owner-occupants looking to offset costs by renting one unit. The 1,119 sq ft property includes two large screened porches and additional open-air spaces. An outdoor shower enhances the island lifestyle. Updates include Mitsubishi mini-split A/C systems in both units, a new hot water heater, new ceiling fans, impact windows upstairs, new gutters, updated appliances, and soft-close cabinetry. Interior finishes feature a mix of pine, vinyl, and concrete flooring, along with stainless, Formica, and butcher block countertops. Both units have full bathrooms with tubs. Additional features include two off-street parking spaces, low-maintenance grounds, and multiple windows for natural light and airflow. Located in Midtown East, the property is near Key West attractions and offers income-producing potential.
    Location Intelligence

    Current Use by Public Records

    Duplexes

    Suggested Use

    Law Firm Real Estate Agency Restaurant Spa & Massage Center Dental Office Hair Salon Nail Salon Building Supply Daycare Center Gym & Fitness Center

    Zoning and permitted uses should be independently verified with local authorities.

    Location Insight

    • Map
    • Local Demand
    City
    Key West
    County
    Monroe
    State
    Florida
    Longitude
    -81.7805905
    Latitude
    24.5567071

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    FAQs

    What type of property is this?
    Duplex - Well-maintained duplex in Key West's Midtown East neighborhood.
    Where is this duplex located?
    The property is located at 1911 Seidenberg Avenue Key West, FL.
    What is the asking price?
    The asking price for this property is $1,250,000.
    What are key features of this property?
    This property features: Legal duplex featuring two separately metered 1‑bedroom, 1‑bath units.; Desirable Midtown East location, close to Key West attractions.; **Updated with Mitsubishi mini‑split A/C, new hot water heater, impact windows upstairs, new gutters, and updated appliances.**
    (305) 294-1117
    We can help!
    Listing Contact
    Everett Smith
    Real Estate License ID: 670558
    Learn More
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    Realmo Value Estimations

    Realmo estimates a property’s market value using a proprietary methodology that incorporates public data and user-submitted information. This cumulative value is generated by integrating a variety of conventional and innovative methods. 

    Disclaimer

    These figures are not official appraisals and should not be used as a substitute for a valuation performed by a licensed appraiser.
    Actual market value may differ due to factors not captured in the data. Estimates are offered for informational purposes only, and users should conduct independent research before making financial or investment decisions.
    By using this feature, you acknowledge that Realmo is not responsible for actions taken based on these estimates.

    AI approach

    Realmo AI Method estimates property value using machine learning models trained on millions of comparable listings, transactions, and market signals. It analyzes property features, location intelligence data, and current market dynamics to predict the most probable market value in real time.

    Realmo CapRate Calculation

    Realmo calculates the Capitalization Rate (Cap Rate) to help estimate a property's potential return on investment. The Cap Rate is a fundamental metric in commercial real estate that measures the relationship between a property's net operating income and its market value.

    How We Calculate Cap Rate

    Cap Rate Formula:
    Cap Rate (%) = (Net Operating Income / Property Value) × 100

    Net Operating Income (NOI) Formula:
    NOI = Area × Lease Rate × (1 - Vacancy Rate) × (1 - Operating Expense Ratio)

    Components

    Net Operating Income (NOI) represents the annual income a property generates after operating expenses:

    • Area: Building square footage from property records
    • Lease Rate: Annual $/sqft based on market data for the property type and geographic location
    • Vacancy Rate: Percentage of unoccupied space based on market data for the property type and location
    • Operating Expense Ratio: Operating costs as a percentage of income, varies by property type

    Property Value is derived from:

    • Recent sale price (if available)
    • Statistical models using comparable sales
    • AI-powered valuation estimates

    Example Calculation

    For a 100,000 sqft Office Building:

    • Lease Rate: $25.00/sqft/year (market data for Office in this area)
    • Vacancy Rate: 8% (market data for Office in this area)
    • Operating Expense Ratio: 35% (typical for Office properties)
    • Property Value: $15,000,000

    Step 1: Calculate NOI

    NOI = 100,000 × $25.00 × (1 - 0.08) × (1 - 0.35)
    NOI = 100,000 × $25.00 × 0.92 × 0.65
    NOI = $1,495,000/year

    Step 2: Calculate Cap Rate

    Cap Rate = ($1,495,000 / $15,000,000) × 100
    Cap Rate = 9.97%

    Property Type Considerations

    Net Operating Income calculations vary by property type due to different operating expense ratios:

    • Office: Higher expenses (30-40%) for HVAC, utilities, maintenance
    • Retail: Moderate expenses (25-35%) for common area maintenance
    • Industrial/Warehouse: Lower expenses (15-25%) for minimal tenant services
    • Multifamily: Moderate expenses (35-45%) including property management
    • Self-Storage: Lower expenses (25-35%) due to minimal maintenance

    Market lease rates and vacancy rates are specific to each property type and geographic location, reflecting local market conditions.

    Disclaimer

    These calculations are estimates for informational purposes only and should not be used as a substitute for professional financial analysis or appraisal.

    • Cap Rate calculations depend on market data that may change over time
    • Actual operating expenses, lease rates, and vacancy rates may differ from market averages
    • Individual property conditions, lease terms, and tenant quality significantly impact actual NOI
    • Property value estimates are approximations and not official appraisals
    • Cap rates vary widely by market, property condition, and investment risk profile

    Professional Guidance Recommended: Before making any investment or financial decisions, consult with licensed appraisers, commercial real estate brokers, and financial advisors who can evaluate your specific property and circumstances.
    By using this feature, you acknowledge that Realmo is not responsible for investment decisions or actions taken based on these estimates.

    Cap approach

    Capitalization Method calculates value based on estimated net operating income (NOI) and applying a market-based capitalization rate (cap rate), we estimate what a typical investor might be willing to pay for it.

    Comparable approach

    Comparable estimate is based on recent sales of similar nearby properties, adjusted for factors like size, condition, and location.

    Relative

    Relative property class coefficient uses factors that account for typical price differences between various asset types (e.g., retail vs. industrial) to provide a more accurate market-aligned estimate.

    Geo

    Comparable Sales Method, enhanced by Geo coefficients — location-based adjustment factors that reflect differences in price levels across neighborhoods, cities, or regions ensuring a more accurate, market-sensitive valuation.

    Stat Estimate

    This method estimates value based on actual market adjusted recent (~5 years) sales of comparable properties around by location and property type.

    • Ranges - area data calculated by industry standard IQR Outlier Removal Method
    • Range-from: 75% of all similar sales ($/sqft) are above this value
    • Range-to: 75% of all similar sales ($/sqft) are below this value
    AI Estimate

    This method estimates value based on AI market estimation of comparable properties around by location and property type.

    • Ranges - area data calculated by industry standard IQR Outlier Removal Method
    • Range-from: 75% of all estimations ($/sqft) are above this value
    • Range-to: 75% of all estimations ($/sqft) are below this value
    Alternative use

    Estimate considers the property’s potential value if used for a different purpose-based on zoning, demand, and market feasibility.

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