The Philadelphia pass is valid for calendar days, not 24 hour periods.
Instructions for online purchases:
After completing an online ticket purchase, an order confirmation, from which e-tickets may be printed, will be sent to the email address provided during checkout.
Printed E-ticket serves as voucher to be redeemed for the actual Philadelphia Pass at Independence Visitor Center (599 Market Street, Philadelphia, PA 19106). Printed e-ticket must be presented at time of redemption.
Note: To purchase tickets online through this system, you must have access to print your ticket(s) before arriving to the attraction. No exceptions.
This E-ticket serves as voucher to be redeemed for physical Philadelphia Pass at Independence Visitor Center (599 Market Street).