The website RamadanMonth.com provides a comprehensive overview of the likely dates for the next Ramadan, including times for Sehr and Iftar for Pakistan on its front page. It also provides downloadable calendars for several other countries, including the United States.
Any calendars published for Ramadan are only estimates until the final few weeks before the event. A moon-sighting committee for each global area confirms the final dates of the start and end of the period in the lunar month prior to the event. This can lead to Ramadan starting and ending on different days in different parts of the world, so using a localized, up-to-date calendar is vital for accuracy. The Islamic Center of America offers a downloadable calendar for Ramadan prayers prior to the start of the period, but this is only available once the committee has confirmed the dates and times for that year.