I plan for min 10% vacancy unless you know precisely that area at any given day.

In the old days before digital mapping, computerized flood simulations, and years of rainfall data, the floodplains were not as precise.

There are still questions on precisely where the line for "advertising" is drawn.

If you want to be even more precise, subtract off closing costs and all the preliminary costs like inspections, dewinterization fees, or surveys.

Precisely @Timothy MaldonadoThis will be by far the most accurate as these are the actual trades & vendors that will install/complete installation/construction.

Can not give you precise information about these topics as I am from Holland but currently working & investing in Barcelona.

I'm Ryan and as the title says I live in NY, in the burbs about 20 minutes outside New York City to be more precise.

This still seems magical to me, as no one has been able to give a clear precise method of making these decisions.

Just a heads up that you should be very precise about comps, streets, zip codes, school districts, etc.

I have a feeling you're leaving out a few major ones in your calculations.To your question on how to value a property: any formulaic way of computing value is going to be inaccurate, as even the most precise require inputs that are a little bit of guesswork (such as prevailing cap-rate for your product type in that neighborhood.)There are some often "rules of thumb" that people use, which are usually used to pass the initial "smell test", but as you will see, will only give you ballpark accuracy.In roughly increasing accuracy and precision:1) Price-Per-Door: see what other multi-family units have sold at, and divide by the number of units.