How to Analyze a Small Multifamily Deal: Cash Flow & Cap Rate

Before you buy a duplex, triplex, or fourplex, you need to know whether the numbers actually work. This guide explains how to run a small multifamily deal analysis step by step: estimating rental income, projecting operating expenses, calculating net operating income, and interpreting metrics like cap rate and cash-on-cash return. The goal is to help owners and buyers of two-to-four-unit properties make decisions based on objective financials rather than guesswork.

Start With Gross Rental Income

Every analysis begins with how much rent the property can realistically collect. Look at the actual rents in place today, then compare them to market rents for similar units in the area.

• Actual rent: what current leases charge right now.
• Market rent: what comparable units lease for, based on size, condition, and features.
• Other income: parking, storage, laundry, or pet fees that are documented and recurring.

Add up the annualized rent for all units to get your gross scheduled income. If a property has below-market rents, note the gap, but underwrite based on current reality and treat future increases as upside, not a given. For help setting realistic figures, see How to Set the Right Rent Price.

Subtract Vacancy and Credit Loss

No property stays 100% occupied forever. Units turn over, and occasional non-payment happens. A common approach is to reduce gross income by a vacancy and credit-loss factor, which varies by location and property type. Subtracting this gives you your effective gross income the money you can reasonably expect to collect.

Project Operating Expenses Honestly

Operating expenses are the recurring costs of running the building not the mortgage. Underestimating them is the most common mistake new investors make. Typical line items for a small multifamily property include:

• Property taxes
• Insurance
• Water, sewer, trash, and any owner-paid utilities
• Repairs and routine maintenance
• Property management (budget for it even if you self-manage, so the deal stands on its own)
• Landscaping, snow removal, or common-area upkeep
• Capital reserves for big-ticket items like roofs, HVAC, and water heaters

Request the seller's actual expense records, but verify them against your own estimates. Taxes often reset after a sale, and insurance quotes should be your own, not the prior owner's. Building a reserve into your budget keeps you from being blindsided; the Rental Property Maintenance guide covers how to plan for these costs.

Calculate Net Operating Income (NOI)

Net operating income is the heart of multifamily analysis:

NOI = Effective Gross Income Operating Expenses

NOI deliberately excludes mortgage payments and income taxes, because it measures the property's performance independent of how it's financed. Two buyers with different loans will calculate the same NOI for the same building which is exactly why it's the standard comparison metric.

Interpret the Cap Rate

The capitalization rate expresses NOI as a percentage of the purchase price:

Cap Rate = Annual NOI Purchase Price

A $400,000 fourplex producing $28,000 in NOI has a 7% cap rate. Cap rates let you compare properties of different sizes and prices on equal footing. They also reflect local market conditions higher cap rates often accompany higher perceived risk or slower-growth areas, while lower cap rates typically appear where prices are high relative to rents. There is no universally "correct" cap rate; what matters is how a property compares to similar buildings in the same market.

Add Financing: Cash-on-Cash Return

Cap rate ignores your loan. Cash-on-cash return measures the actual return on the money you put in:

Cash-on-Cash = Annual Pre-Tax Cash Flow Total Cash Invested

Annual cash flow is NOI minus your annual mortgage payments (principal and interest). Total cash invested includes your down payment, closing costs, and any upfront repairs. This metric tells you how hard your actual dollars are working, factoring in leverage.

Financing Basics for Two-to-Four Units

Small multifamily properties occupy a useful lending niche. Two-to-four-unit buildings are generally financed with residential mortgages rather than commercial loans, which often means more favorable terms and lower down payments than five-plus-unit properties.

• If you plan to live in one unit, owner-occupant financing may allow a smaller down payment. Many lenders also let you count a portion of the projected rent from the other units toward qualifying income.
• Pure investment purchases typically require larger down payments and may carry slightly higher rates.
• Reserves lenders often want to see several months of payments in the bank at closing.

Getting pre-approved early tells you your real budget before you fall for a property. See Mortgage Pre-Approval Explained. If you intend to occupy a unit yourself, the House Hacking a Duplex or Fourplex guide walks through that strategy in depth. Loan terms, rates, and qualifying rules vary by lender and location consult a licensed mortgage professional for your specific situation.

Build a Simple Deal Screen

Before touring anything, screen deals quickly with a repeatable checklist:

• Confirm the number of legal units and their configuration.
• Gather current rents and compare to market.
• Estimate expenses at realistic levels, including reserves and management.
• Calculate NOI, cap rate, and cash-on-cash return.
• Compare the results against other properties in the same area.

If a deal passes your screen, you can move toward a formal offer and inspection. Ready to list or browse available properties? You can create a listing or explore homes for sale on the buy page.

Frequently Asked Questions

What is a good cap rate for a small multifamily property?

There is no single "good" number. Cap rates reflect local market conditions, property condition, and risk. The practical approach is to compare a property's cap rate to similar two-to-four-unit buildings in the same area rather than to a national benchmark.

How is a fourplex financed differently than a larger apartment building?

Properties with two to four units generally qualify for residential mortgages, while buildings of five or more units typically require commercial loans. Residential financing often offers lower down payments and more standardized terms, which is why small multifamily is a popular entry point.

Should I include property management costs if I plan to self-manage?

Yes. Budgeting for management even if you do the work yourself ensures the deal stands on its own and reflects the true cost if you ever hire out. It also protects your analysis if your situation changes later.

What expenses do new investors most often overlook?

Capital reserves for major replacements, post-sale property tax increases, your own insurance quote (not the seller's), and realistic vacancy allowances. Underestimating these inflates projected returns and leads to disappointment.