Best way to calculate Market Rent Level?

[Darek J.]

Hello all, 

I have a unit that will be up for lease renewal in the next month or so. In preparation for that, I have been keeping an eye on other properties in my general are. I have a duplex, the unit is a 3/2, so I've been keeping an eye on other apartments/SFH/multiunits within about 1 mile over the last 3-4 months. Each week I look at both craigslist and hotpads to put each rental ad's info onto a spreadsheet for easy analysis. I track things such as date, rent, deposit, sqare footage, number of bed/baths, address, etc. At this point I have 28 data points.

Based on price per square foot, after averaging the properties around me, my spread sheet is telling me I should raise rents by about $35 from $1200.  HOWEVER, when I run the property address through Rentometer.com, I get that my rent should increase by $150-200, to $1400.  Zillow.com lists a rent for that unit at $1295. 

So here's my question...Which do I go with?  How do you calculate your market rents?  My gut tells me go with the spreadsheet and historical data over the last 3-4 months.  $35 seems reasonable. I don't think it would be best practices to increase rents that much ($100-200) anyway.