Whether you’re thinking about buying a duplex in Portland, Oregon, or you’re an owner considering selling one, understanding how investors determine property value is essential. How do you know if a duplex is priced correctly? How do you determine what your Portland duplex is actually worth? And if you’re evaluating a triplex or fourplex, which numbers should you pay attention to?
There isn’t one magic formula that determines the value of a small multifamily property. Instead, experienced investors look at several different valuation methods, compare the results, and then apply their own judgment.
When I evaluate a Portland duplex, triplex, or fourplex, I like to use four different approaches: price per unit, price per square foot, gross rent multiplier, and capitalization rate. Each provides a different perspective, and together they help create a more complete picture of a property’s value.
1. Price Per Unit
The simplest way to begin valuing a duplex or other small multifamily property is to calculate its price per unit.
The math is straightforward: divide the property’s purchase price by the number of units.
For example, if a Portland fourplex is listed for $848,000, the price per unit is $212,000. You can then compare that number with other recently sold fourplexes in the area to get an initial sense of whether the property is priced reasonably.
Price per unit is useful because it doesn’t require much information. You don’t need to review the rent roll, analyze expenses, or calculate operating income. It’s a quick way to establish a starting point.
However, there’s an important limitation: not all units are created equal.
A fourplex consisting of four studio apartments is very different from a fourplex with four three-bedroom units. Even within the same building, unit sizes and layouts can vary considerably. A property with two smaller units and two larger units shouldn’t necessarily be valued the same as a property with four identical apartments.
Price per unit is a helpful starting point, but it shouldn’t be the only method you use to determine the value of a Portland duplex, triplex, or fourplex.
2. Price Per Square Foot
The second approach is to calculate the property’s price per square foot.
To do this, divide the purchase price by the total living area of the building.
For example, a fourplex with 3,200 square feet of living space selling for $960,000 has a price of $300 per square foot.
This method helps account for differences in unit sizes. It can be particularly useful when comparing properties with unusual unit configurations, such as a house with an accessory dwelling unit or an older building that has been converted into multiple units.
But price per square foot has limitations, too.
Smaller units often command a higher price per square foot than larger units. That’s partly because certain construction costs, such as kitchens, plumbing, and appliances, are relatively fixed regardless of the overall size of the apartment.
The quality of the finishes also matters. Two 800-square-foot apartments might have identical square footage, but one could have dated cabinets and appliances while the other has been completely remodeled with higher-quality materials.
Those differences can have a meaningful impact on value, even though the price-per-square-foot calculation doesn’t account for them.
3. Gross Rent Multiplier (GRM)
The third method shifts our attention from the physical characteristics of a property to its financial performance.
Gross rent multiplier, commonly called GRM, compares a property’s purchase price with the gross rental income it generates.
The calculation is:
Purchase Price ÷ Annual Gross Rental Income = Gross Rent Multiplier
For example, if a duplex generates $5,000 per month in gross rent, its annual gross rental income is $60,000. If the property sells for $600,000, its gross rent multiplier is 10.
To determine whether that is a good number, you’ll need to compare it with other similar properties that have sold in the same market.
One important distinction: sellers generally prefer a higher GRM because it indicates a higher purchase price relative to rental income. Buyers, on the other hand, generally prefer a lower GRM.
Another consideration is whether the property’s current rents accurately reflect market rents.
For example, a Portland fourplex might have tenants paying $1,400 per month when comparable units could reasonably rent for $1,800. In that situation, I would calculate the GRM using both the actual rents and the potential market rents.
The existing rents tell you what the property is producing today. The market rents help you understand its potential.
That distinction can be particularly important when evaluating an investment property with below-market rents and opportunities to improve its performance.
4. Capitalization Rate (Cap Rate)
The fourth method is capitalization rate, commonly called cap rate.
Cap rate measures a property’s annual net operating income relative to its purchase price.
The calculation is:
Annual Net Operating Income ÷ Purchase Price = Cap Rate
Net operating income, or NOI, is the rental income remaining after operating expenses have been paid. These expenses include items such as property taxes, insurance, maintenance, utilities, and property management. Mortgage payments are not deducted.
For example, if a property generates $100,000 in annual rental income and has $40,000 in operating expenses, its annual NOI is $60,000.
If the property sells for $1 million, the cap rate is 6%.
Unlike GRM, buyers generally prefer a higher cap rate, while sellers prefer a lower cap rate. A higher cap rate means the buyer is receiving a greater return relative to the purchase price.
One important caution: cap rate calculations depend on the accuracy of the income and expense numbers. If a seller or listing agent leaves out property management expenses, understates taxes, or excludes other operating costs, the advertised cap rate may be misleading.
Don’t simply accept someone else’s cap rate calculation. Review the underlying numbers and determine what the actual operating expenses are likely to be.
Although cap rate may not be the primary valuation method used in a residential appraisal for properties with four units or fewer, I still think it’s a valuable additional data point for buyers and sellers evaluating Portland small multifamily real estate.
The Most Important Factor: Understand the Competition
Here’s the lesson I learned the hard way: comparable sales are important, but you also need to understand the competition.
When valuing a Portland duplex, triplex, or fourplex, it’s easy to spend hours analyzing spreadsheets, calculating price per unit, comparing price per square foot, and evaluating GRM and cap rates.
You should do those things. But the calculations don’t tell the entire story.
You also need to look at the other properties a potential buyer would consider.
Imagine you’ve determined that your triplex is worth $900,000 based on all four valuation methods. But when you look at the current competition, you discover another similar property listed for $850,000. You also find a fourplex listed for $900,000.
Would a buyer choose your three-unit property over those alternatives?
That’s where you need to apply some common sense and look at the property through the eyes of a potential buyer.
Location, traffic, noise, condition, layout, finishes, and overall desirability all influence how buyers perceive value. Some of these factors are difficult to capture in a spreadsheet, but they can make a substantial difference in whether a property attracts offers.
I learned this lesson while selling a house I had renovated. The comparable sales suggested a $400,000 value, so that’s where we priced it. Unfortunately, we received very little interest. When I stepped back and looked at the competing properties from a buyer’s perspective, I realized our house wasn’t as desirable at that price as the numbers had suggested.
The lesson applies just as much to duplexes, triplexes, and fourplexes.
Putting It All Together
When I evaluate a Portland duplex or other small multifamily property, I like to triangulate value using all four methods:
- Price per unit
- Price per square foot
- Gross rent multiplier
- Capitalization rate
Then I take those numbers and compare the property with its actual competition.
The goal isn’t simply to arrive at a number that makes sense on paper. It’s to determine a price that makes sense in the marketplace.
If you’re buying, you want to know whether the property represents a good value compared with your other options. If you’re selling, you want to price your property so that buyers see it as one of the most attractive choices available.
Whether you’re considering a duplex for sale in Portland, evaluating a Portland triplex investment, or preparing to sell a fourplex, understanding these valuation methods can help you make a more informed decision.
If you’re thinking about buying or selling a duplex, triplex, or fourplex in Portland, I encourage you to start the conversation early. The more time we have to evaluate the property, review the numbers, understand the competition, and develop a strategy, the better prepared you’ll be.
I also publish monthly market reports specifically covering Portland and Central Oregon duplexes, triplexes, and fourplexes. These reports provide useful context for understanding prices per unit, prices per square foot, days on market, and overall market activity.
You can reach me at 503-869-7303 to discuss your next small multifamily purchase or sale.
