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    Two-Family Waterfront Home Title is generated by Realmo AI

    25 South Mill Street, Portsmouth, NH 03801

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    Claim this Listing
    For Sale
    Under Contract
    $1,795,000

    MULTI_FAMILY - Other - Portsmouth, NH

    Property size:
    1,760 SF
    Lot size:
    0.12 Acres
    Price / SF:
    $1,019/SF
    Added:
    Jan 6, 2026
    Days on Market:
    149
    Last Refresh:
    Jun 4 at 7:06 am

    Property Features for 25 South Mill Street

    General Information

    Property type
    Residential Multi Family
    Property subtype
    Other
    Zoning
    GRB
    Bedrooms
    4
    Bathrooms
    2
    Rooms
    Bathroom 2, Bedroom 3, Bathroom 1, Bedroom 2, Bedroom 1, Basement, Bedroom 4
    Parking features
    Garage
    Standard status
    Active Under Contract
    Size
    1,760 SF
    Lot size
    0.12 Acres

    Taxes and HOA fees

    Tax Year
    2025
    Tax Annual Amount
    14253

    Utilities

    Utilities
    Propane
    Heating system
    Hot Water(Heating)
    Water source
    Public

    Building Details

    Year built
    2013
    Floors in Building
    2
    Number of units
    2
    Flooring type
    Wood, Carpet
    Building materials
    Clapboard Exterior, Wood Siding
    Roof type
    Shingle
    Architectural style
    Other

    We can help!

    Listing Contact
    Emil Uliano

    Listing agent Emil Uliano

    Listing office Great Island Realty LLC 40 Pleasant St., Portsmouth, NH

    Listing date Jan 6, 2026

    MLS# 5073158 Listing URL

    Copyright © 2026 PrimeMLS. All rights reserved. All information provided by the listing agent/broker is deemed reliable but is not guaranteed and should be independently verified.

    HighLights

    • Built in 2013 two‑family home in Portsmouth’s South End neighborhood
    • Two units with 2 bedrooms, 1 full bath, and in‑unit laundry
    • Waterfront location with elevated views from the upper unit
    • Garage parking plus a driveway that accommodates 6+ vehicles (oversized garage approx. 14' x 26')
    • Utilities include propane; water source is public; heating is hot water; roof is shingle
    • Upper unit is vacant; lower unit leased through April 2026 (most recently rented in 2025 for $2,900/month)

    Overview

    Built in 2013, 25 South Mill Street is a two-family home designed for practical day-to-day living. Each unit offers two bedrooms, one full bathroom, and in-unit laundry. The upper unit is currently vacant, making it easier to tour and plan occupancy, while the lower unit is leased through April 2026.

    The property is situated on the waterfront in Portsmouth, with a setting described in the remarks as part of the South End area. Parking is a standout feature for the configuration: the property includes a deep, oversized garage (approximately 14' x 26') plus a driveway that accommodates 6+ vehicles. Zoning is listed as GRB.

    This layout supports multiple ownership paths, including an owner-occupant scenario where one unit can offset housing costs, or an investor purchase centered on steady rental continuity through the end of the existing lower-unit lease term. The current vacancy in the upper unit also adds near-term flexibility for renters, residents, or buyers planning to occupy while maintaining income from the lower unit. Plans for alternative uses are referenced in the remarks, including condo conversion or conversion to a single-family residence; buyers should confirm feasibility with appropriate local requirements.
    Property Profile Location Intelligence

    Current Use by Public Records

    BCB Appraisals Real Estate Agency

    Suggested Use

    Real Estate Agency Law Firm 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
    Portsmouth
    County
    Strafford
    State
    New Hampshire
    Longitude
    -70.7502045
    Latitude
    43.0731887

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    FAQs

    What type of property is this?
    Duplex - Newer two-unit waterfront residence with in-unit laundry, oversized garage, and flexible occupancy for an owner or investor.
    Where is this duplex located?
    The property is located at 25 South Mill Street Portsmouth, NH.
    What is the asking price?
    The asking price for this property is $1,795,000.
    What are key features of this property?
    This property features: Built in 2013 two‑family home in Portsmouth’s South End neighborhood; Two units with 2 bedrooms, 1 full bath, and in‑unit laundry; Waterfront location with elevated views from the upper unit
    (603) 433-3350
    We can help!
    Listing Contact
    Emil Uliano
    Request Owner's contact information
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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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