The halfway point of a typical calendar year is July 2, which is the 183rd day of a 365-day year. The halfway point of a leap year, which is 366 days long, is July 1.
The precise midpoint of a year of either length is noon of the specified day. This does not take into account that one year by the Western, or Gregorian, calendar, which relies on the movement of the sun, is slightly longer than 365 days but shorter than 366 days. July 1 or July 2 is also only mid-year by this particular calendar. The lunar calendar year is only 354 days long.