Question about Vacancy Rate Calculation

[Michele Velazquez]

Ok, I hope I can ask this correctly.  I am buying 4 townhomes in Austell, GA.  I used this calculator to determine if the property cash flows:

https://www.calculator.net/ren...

As you can see, I did use a 5% vacancy rate and 8% for property management.  However, in addition to the 8% a property manager charges, there is also a one months rent fee to get a tenant and a lease renewal fee.  Now I am freaking out that I didn't calculate for any of that and so are my calculations wrong?  Where and how are you supposed to account for losing an entire months rent to get a tenant?  HELP! 

[Chris Seveney]

@Michele Velazquez

This is why carrying 12-15% vacancy is typically more accurate on single family - 4 unit properties.