Capital gains tax calculation

[Pavan Sandhu]

Hello, I am looking to purchase a home. It’s been in the sellers family for many decades until he inherited the property in the 80s. If/when he sells he will be hit with capital gains taxes. As a buyer I’d like to calculate a rough amount of what he would be looking at in capital gains taxes.

Yes the first 250k would be exempt but after that what’s his potential tax hit? He is a low to modest income earner in CA.

Any advice or direction would be appreciated.