How to Calculate ARV Without an Appraiser
You've got a property under contract, or you're about to make an offer, and you need to know what it'll be worth after you fix it up. An appraisal costs $400 to $600 and takes three to seven days you don't have. So you're doing what every investor does at 11pm with a deadline: pulling comps yourself.
Here's the answer. Find three to five homes that sold in the last six months, within half a mile of your subject property, similar in square footage, bed count, and bath count, and that were already renovated when they sold. Take their sale prices, divide each by square footage to get price per square foot, average those numbers, then multiply by the finished square footage of your subject property after your planned repairs. That's your ARV.
The math is simple. The part people get wrong is the comp selection, and that's where a $30,000 estimate error usually comes from.
What Counts as a Real Comp
A comp is a recently sold, renovated property that's similar enough to yours that a buyer would consider them interchangeable. Four filters matter more than the rest:
Sold, not listed. An active listing is someone's opinion of value. A closed sale is what a buyer actually paid. If you're using Zillow's "for sale" tab to build your ARV, you're building it on guesses. Filter for sold status only.
Recent. Six months is the standard cutoff. In a market moving fast, tighten that to 90 days. A comp from fourteen months ago tells you what the market was, not what it is.
Close by. Half a mile is the rule of thumb in a normal suburban market. In a dense urban neighborhood, two or three blocks. In a rural area, you may have to stretch to two miles, and you should discount your confidence accordingly. School district lines and busy roads can cut a comp's relevance even at a quarter mile.
Renovated condition. This is the one people skip. If you're calculating ARV, the whole point is estimating value after your repairs. A comp that sold as a fixer-upper doesn't tell you that. You need comps that sold finished, updated, move-in ready, because that's the condition your subject property will be in when you're done.
Why Price Per Square Foot and Not Just Sale Price
Two houses can both be "3 bed, 2 bath" and differ by 600 square feet. If you just average their sale prices, you'll get a number that means nothing. Price per square foot normalizes for size, which is why it's the standard unit for comps.
It's not perfect. A 900 square foot house and a 2,800 square foot house on the same street usually don't have the same price per square foot, because smaller homes carry a premium per square foot and larger ones a discount. That's why the half-mile, similar-size rule matters. Compare houses that are within 20 percent of your subject's square footage when you can.
What People Get Wrong
The most common mistake is comping to the highest sale on the street and calling it done. One comp is not a comp set. If one of your five comps sold for $210 a square foot and the other four sold between $165 and $175, that outlier is doing something you don't understand yet, maybe a bidding war, maybe a finished basement your subject doesn't have. Investigate it or drop it. Don't let one number pull your average.
The second mistake is ignoring lot size and layout differences. A comp on a double lot, or a comp with a garage when your subject has none, needs an adjustment, not a blind average. If you can't quantify the adjustment, note it as a reason to lean toward the lower end of your range.
The third mistake is comping to full renovations when your budget only covers a mid-tier rehab. If your comps have quartz counters and white oak floors and your rehab budget is $35,000 for a 1,600 square foot house, you're not getting that finish level. Your ARV should reflect the renovation you can actually afford, not the nicest recent sale in the ZIP code.
A Worked Example
Say you're looking at a 1,500 square foot, 3 bed, 2 bath ranch built in 1978. You pull five renovated comps within half a mile, all sold in the last four months:
- 1,480 sq ft, sold $268,000 → $181/sq ft
- 1,550 sq ft, sold $274,500 → $177/sq ft
- 1,420 sq ft, sold $251,000 → $177/sq ft
- 1,600 sq ft, sold $291,000 → $182/sq ft
- 1,510 sq ft, sold $263,000 → $174/sq ft
Average price per square foot: ($181 + $177 + $177 + $182 + $174) / 5 = $178.20
Multiply by your subject's 1,500 square feet: $178.20 x 1,500 = $267,300
That's your ARV: roughly $267,000. Now check it against the math that matters for your offer. If your all-in cost is $190,000 purchase plus $40,000 rehab, that's $230,000 total. Against a $267,000 ARV, you've got $37,000 of spread before selling costs and holding costs, which is thin for many investors' target margins. This is exactly why you calculate ARV before you write the offer, not after.
Cross-Check With a Second Method
Don't stop at one comp set. Pull public tax records or MLS sold data a second way, by searching sold listings directly instead of relying on an automated estimate tool. If your manual comp average and a third-party estimate land within 5 percent of each other, you can trust the number. If they're 15 percent apart, something's off, usually a bad comp on one side or the other, and you need to dig into which comps are actually comparable before you commit real money to an offer.
The Honest Limitation
This method gets you within striking distance of a licensed appraisal, usually within 5 to 10 percent in a market with enough recent sales activity. It will not replace an appraisal for a lender, and it gets shakier in thin markets: rural areas, unusual properties, or neighborhoods with few recent sales. If you can only find one or two real comps within a reasonable distance and timeframe, treat your number as a rough range, not a precise figure, and build in more margin before you commit to a purchase price.
This is manual work, and it's worth doing by hand at least a few times so you understand what a comp actually is and why one gets excluded. Once you trust the process, Deal Machine pulls the comps and runs this math for you on every property you're evaluating, so you can move from address to ARV in minutes instead of an evening. You can try it at readmoneydecoded.com/deal-machine.