Seeded fourth in the draw, Sinha seemed confident from the beginning, winning the opening set 6-4.
In the second, Jagtiani came back with good use of the net game to win 6-3.
In the decider, Sinha proved to be too good for Jagtiani drubbing the favourite 6-3, thereby winning the title.
Featuring in his second final in the U-18 section where he was unseeded, Jagtiani gave second seed Deepak Vishavkarma from Delhi a stiff challenge before going down 6-7 (2), 6-4, 2-6.
Local girl Shruti Gupta won the girls singles U-14 title, whereas Arushi Bhasin from Delhi won the U-18 crown.
Results: (All finals, Bengal unless specified): Boys Singles U-14: Nitin Kr Sinha (4) bt Sanil Jagtiani (2) 6-4, 3-6, 6-3; Boys Singles U-18: Deepak Vishwakarma (Del)(2) bt Jagtiani 7-6 (2), 4-6, 6-2; Girls Singles U-14: Shruti Gupta (1) bt Koyal Mishra (Ori)(4) 6-3, 7-5; Girls Singles U-18: Arushi Bhasin (Del)(4) bt Shreya Das (6) 6-2, 6-4.