Abstract: A system and method for cross-platform targeting includes: receiving as input calendar entries from an on-line calendar associated with a first user, the calendar entries designating specified time slots associated with scheduled events; marking the specified time slots associated with the scheduled events as unavailable time slots; eliminating the unavailable time slots from the calendar associated with the first user; determining from remaining time slots those time slots wherein the first user is deemed unlikely to be available; removing those time slots from the calendar, providing free time slots; and presenting the free time slots as optimal time slots for serving digital information to the first user.