Concept
Fudge Factor
What it is
Fudge factor is the dollar adjustment you make to a comp when it doesn’t perfectly match your subject property. Your house has 3 bedrooms, the comp has 2. Your house has a garage, the comp doesn’t. Your house has a pool, the comp doesn’t. Each of those differences is worth a specific number of dollars in your market, and fudge factor is how you apply those numbers to turn a rough comp into a useful one.
The core rule: fudge one variable at a time, and never fudge proximity. If a comp has the same beds, same baths, same age, same square footage, but it’s across a major road or in a different school district, that’s not a comp. Distance and location are the two variables you can’t adjust your way around.
I teach pulling comps by three things: features, date sold, and proximity. Date sold you want within about six months, maybe 12 if there aren’t many houses to compare. Proximity means you want the house in the same neighborhood — and figuring out the real boundaries of a neighborhood is itself a key skill. Same square footage, same bed/bath counts, same general era of construction. Then you make the adjustments for whatever doesn’t match.
Why it matters
Fudge factor is what separates a real ARV from a Zillow guess. Anyone can pull five sold comps within half a mile. A pro knows that the comp with the extra bathroom is worth a specific dollar premium, and the comp without a garage requires a specific adjustment in the other direction. Apply those and you get a defensible ARV.
New flippers either skip adjustments entirely (and overpay) or overdo them (and talk themselves into a fake ARV). Both fail. The discipline is to know your market’s typical adjustment values: what’s an extra bedroom worth in your price range, what’s an extra full bath, what’s a garage, what’s a finished basement. These numbers vary by market — calibrate against your local sales, not rules of thumb from a podcast.
This is also why comping is a skill, not a spreadsheet. Two flippers can look at the same 10 comps and come up with ARVs $15K apart. The one who’s been doing it longer is usually right because they know which variables to weight and which to ignore.
How it shows up
Typical adjustment: your subject is a 3/2 with 1,200 sqft and a one-car garage. You pull a 2/1 comp that sold for $165K in the same neighborhood. Make the adjustments for the extra bedroom and bath, leave the garage (same), and you get your adjusted comp value. Pull three or four more, adjust each one, average the range. That’s your defensible ARV.
The traps. Fudging proximity — “this comp is in a better neighborhood but it’s only a mile away, so I’ll adjust $10K.” No. Wrong side of the tracks can miss ARV by $100K-plus. That is not adjustable. Fudging condition — “this comp was a gut reno but mine will be nicer.” Don’t adjust up for your own optimism. Match condition class to condition class.
When in doubt, throw the comp out. Three great comps beat eight mediocre ones. The fudge factor is a refinement tool, not a rescue tool. If a comp needs more than one major adjustment, it probably isn’t a comp.