Custom Duty requirement for 2 iphones from USA to India

[Jeetanshu.shah]

I will be traveling back to India (Bangalore specifically) from the USA next month. I was on a business visit for 3 months. While here, i purchased a new iphone 6s for my sister. I have an iphone 6s myself, which i had purchased from Singapore a year back. Also, i have 2 laptops with me, one from my company and another personal one.
1. Will i need to declare both my iphones at customs? Or can i expect to clear customs without any problems?
2. Will they charge any duty? If yes,Approximately how much?
3. Any other declaration i need to make? I am not carrying any other electronic items apart from these.

Thanks