Bought at 70 percent of ARV, sold at ARV, made 46,800
This was a rental I got talked into flipping instead, and the arithmetic looked airtight on paper.
ARV 288 from three comps within a quarter mile, all closed inside 90 days. Repairs 32. So 0.70 x 288 = 201.6, minus 32 = 169.6 max purchase. I bought at 166. Under the line. Sold at 288, exactly the ARV, in 21 days.
Made 46,800, and I still think of it as a loss.
Where it went. Repairs came in at 39.8, not 32, because the LVP install found a slab crack that needed leveling compound and the bathroom vent had never been vented anywhere, so I paid to run it out the roof. That's 7.8 over. Holding was five months, not the three I planned, because I started in November and lost most of December to nobody showing up, at 2,180 a month all-in with debt service, so 10,900 instead of 6,540. Selling cost 6 percent plus title and a 2,600 buyer credit after inspection, 20,100 total. Acquisition closing 4,400.
166 + 39.8 + 10.9 + 20.1 + 4.4 = 241.2 against 288. That's 46.8 of gross, and then my own labor was roughly 240 hours of demo, painting, and hauling that I never priced. Priced at even 60 an hour that's 14,400 I never wrote down.
The error is that I treated the 70 percent rule as covering my costs when it's a screening filter for the purchase decision and nothing else. It doesn't know my carry, my rate, my season, or that I'd work for free.
What I'd do differently: build the actual dollar model before the rule, and if the dollar model and the rule disagree, the rule loses. Also don't start a flip in November.