The right way to calculate equity?

[Mahmoud Tellou]

Hello awesome Bigger Pocketers, major Newbie here! The question is related to calculating equity. Let's say I put 20% down on a $100K property so now have $20K in it. The question is:

If I put in an X amount of $'s into the property and the ARV is now say $130K would my equity be 20% of the $130K? Or would it remain at $20K?

To make it short is equity calculated based on the % of what I own of the property or the money I put in? Thanks everyone!