On the SoFi mobile app, buying power is displayed near the top of your Active Invest below the performance section. If you tap on your buying power, you can see more information. Buying power is also displayed on the top-right corner of the order entry page. If you have Margin Trading enabled, the available margin funds are included in your buying power.
On SoFi.com, buying power is displayed within the My Holdings section of your Active Invest account summary section. Buying power is also displayed near the top of the order entry page. If you have Margin Trading enabled, the available margin funds are included in your buying power.