Estimating Repair Costs and CapEx

[Shiv Gettu]

Hi everyone!

I'm a new investor and wanted to get a better understanding of how to accurately assess costs. I've been using the BiggerPockets calculators to run numbers, but my one concern is: how do you vett the accuracy of your numbers? 

For instance, how would I get an accurate estimation on CapEx fees if I am just looking at the listing online, and how do you precisely differentiate between different CapEx fees? Or the Repairs and Maintenance costs of each house? I know it probably varies based on the parameter "Age of property", but it still seems very subjective and difficult to get accurate estimations on some of your numbers.

What do folks do to ensure accurate estimations regarding CapEx, Repairs and Maintenance, Vacancy rates, and ARV?

Thanks a ton in advance :)