Eid Mubarak and may every year find you in peace.
In our part of the world, the Eid will be celebrated tomorrow although in most part of the World the EID is celebrated today and that aligns with moon sight accroding to the Saudia Arab.
The Sunnah states that the new month starts on the evening when the waxing crescent moon is first sighted. Depending on your location (and weather, obviously,) the month can be 29 or 30 days long. Mathematically speaking, the average synodic cycle is 29.53 days, so that tracks.
In North America (and most of the Northern Hemisphere west of Far East) the moon was spotted last night, so we celebrated Eid today. Some celebrated yesterday, and others will celebrate tomorrow.