In general, there is not much difference in using a VPN app versus other apps on your iPhone when it comes to battery consumption. Battery consumption when a VPN is off is near zero, and when it’s turned on, it consumes comparable battery power to any other phone task might. However, high central processing unit (CPU) usage may occur when certain robust VPNs are turned on, which can result in less battery life. Be sure to check and see the processing power needed for different VPNs if this is a main concern of yours.