It says - "A minimum of 250 square inches on head, chest and back, combined, visible 360 degrees"
The actual code is PA Title 34, Chapter 25, Section 2524
Sec. 2524. Protective material required.
(a) General rule.--Unless further restricted by regulations of the commission, every person hunting for or assisting to hunt for deer, bear or woodchucks shall wear either a minimum of 250 square inches of daylight fluorescent orange-colored material on the back and front combined or, in lieu thereof, a hat of the same color material. The material shall be worn so it is visible in a 360-degree arc. Unless otherwise specified by regulations of the commission, the provision of this section shall not apply to any season for using muzzle-loading firearms only or season for using bows and arrows only.
(b) Penalty.--A violation of this section is a summary offense of the fifth degree.
The actual regulation which restricts the above law - Sec 141.20 - states nearly identical wording to the "head, chest and back, combined,"