How long does it take to transfer data from iPhone to iPad?

The time required will be determined by many factors, including but not limited to:

• how much data must be transferred/restored
• the speed/throughput of your internet connection
• the speed/throughput of your WiFi network
• server loading; assuming an iCloud backup, Apple’s regional servers may be busy

The only aspect that you may be able to directly influence is your WiFi network. You should note, however, that the slowest item in the chain will ultimately be the limiting factor.

What exactly are you trying to do?

iPads and iPhones generally do not ever “interconnect” or transfer data directly with each other.

1 hour or 45 minutes