Financial Equation for Offers

[Cassandra Alessio]

Hey!

Does anyone have a certain formula to determine the highest offer for a certain property which includes some upgrades? I know by looking at comparables you can determine how much could be made on a property but how do you work backwards? Is there a certain percentage that could be good to used for upgrades (simple upgrades vs major projects) or is it just that you have to know specific costs for upgrades? 

Thank you!