Custom Field Data from other colume

I buy item from other currency and sell it in my locate currency, can I add the new custom field in inventory section to sum the real cost in our locale currency.
SKU | Desc | Buy Price (In EUR) | Sell Price (In USD) | Amount | Cost | Custom Field with the value = Buy Price x Exchange Rate

You can add custom field but there won’t be any logic associated with it. For now, the sale price will need to be updated manually as needed.