Small Aircraft; High Wing; 1 Eng; Fixed Gear
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 65; Flight Crew Total 780; Flight Crew Type 650
Workload; Situational Awareness; Confusion; Communication Breakdown; Distraction
Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Air Traffic Control Issued Advisory / Alert
Environment - Non Weather Related; Human Factors
I departed ZZZ and was enroute to ZZZ1 before direct LR at 2;500 to avoid Bravo airspace.  I identified that a short tail of Bravo I could vector to the final course at 2;500 and remain below the shelf.  The next step would be to 3;500 in a 4;000 shelf of Bravo.  I was monitoring Center departure and several traffic calls were made about me at 2;500.  I kept identified each target and stated clear. I considered identifying that I was on frequency; but he was very busy.  I glanced at my iPad between traffic spots and saw a 4;000 shelf and mistakenly thought I was in the 4;000 shelf so I climbed to 3;500.  The ZZZ2 traffic was held at 4;000. I only went 3;000-3;500 the final 1-2 mi of the shelf (1 minute at my speed) and when he identified me at 3;500; I realized; I wasn't where I thought I was and by then; I was crossing into the 4;000 shelf. Distraction by watching traffic diverted my attention so that a glance misidentified the shelf of Bravo.  I have flown in Bravo for X yrs without violating it.  Flight following would have prevented this; but with the controller cut backs; they are so overworked in Center; I did not think I needed it.
Pilot reported experiencing a Class B airspace violation.