How to run comps real estate style — properly, not just glancing at Zillow — is what changed how I see Philadelphia entirely.
When I was flipping houses in Los Angeles, the baseline was a million dollars. Not a nice house. Not a renovated house. Just a house. A basic, nothing-special house in a nothing-special neighborhood. The math was brutal. The margins were thin. One mistake and your profit disappeared.
Then I came to Philadelphia and started walking neighborhoods.
In Germantown, I found houses selling for $110,000. Not abandoned shells — actual houses with bones and potential. Renovated comps going for $150,000, $180,000, sometimes $200,000. Churches being converted into loft apartments. Old factories becoming something remarkable.
That’s what comps showed me. And that’s why I’m still here.
What Comps Actually Are
Comps — short for comparable sales — are the recent sale prices of properties similar to the one you’re analyzing.
They answer one question: what is this property actually worth in today’s market?
Not what the seller is asking. Not what Zillow’s algorithm estimates. What similar properties in the same neighborhood have actually sold for, recently, to real buyers.
This is the foundation of every serious real estate calculation. Your ARV — After Repair Value — is only as accurate as your comps. Get the comps wrong and every number downstream is wrong too.
How to Run Comps Real Estate Investors Actually Use
The tools are free. What matters is how you use them.
Zillow and Redfin are your starting points. Both show recent sold prices — not just active listings. Filter for sold properties and you’ll see what buyers actually paid.
Philadelphia’s public property records are available through the Office of Property Assessment. Look up any address and see the sale history, assessed value, and square footage — for free.
Walking the neighborhood is something no algorithm can replace. I do this in Germantown regularly. I look at what’s been renovated, what’s still distressed, what’s under construction. The physical reality of a block tells you things Zillow can’t.
The Criteria That Matter When You Run Comps Real Estate Style
Not every sold property is a useful comp. Here’s what to look for:
- Similar size — within 200 to 300 square feet of your target. A 1,200 sqft house and a 2,000 sqft house aren’t comparable even on the same block.
- Similar bedroom and bathroom count — they serve different buyers at different price points.
- Same neighborhood — ideally within a half mile. Philadelphia neighborhoods can change dramatically within a few blocks.
- Sold within 90 to 180 days — a sale from two years ago tells you where the market was, not where it is.
- Similar condition — when evaluating a flip, you want comps of renovated properties. That’s your ARV target.
A Real Germantown Example
I walked a block in Germantown recently and looked at three properties sold in the past six months:
- Property 1: 1,400 sqft, 3 bed 1 bath, fully renovated — sold for $165,000
- Property 2: 1,350 sqft, 3 bed 1 bath, updated kitchen and bath — sold for $148,000
- Property 3: 1,500 sqft, 3 bed 2 bath, full renovation — sold for $195,000
Average price per square foot: ~$113/sqft.
Looking at a 1,400 sqft distressed property on the same block? ARV estimate: ~$158,000. From there, apply the 70% rule, subtract renovation costs, and you have your maximum offer price.
That’s how to run comps real estate investors actually use. Not complicated — but only useful if you’re pulling the right data.
Want to run it yourself? The Comps Analyzer does exactly this — enter up to five recent sales and it calculates your ARV and maximum offer price automatically.
What Philadelphia Taught Me That Los Angeles Couldn’t
In Los Angeles, a 5% mistake on a million dollar property is $50,000. In Philadelphia, a 5% mistake on a $150,000 property is $7,500 — still meaningful, but survivable. The market is more forgiving of the learning curve.
And the upside is real. All around me in Germantown, I see churches, factories, and warehouses being transformed. I want to be part of that.
The comps tell me the opportunity is real. The numbers don’t lie.
Not financial advice — just someone doing a lot of research and asking a lot of questions.