According to which calendar is new year's celebrated on january 1st?

Gregorian calendar

Explanation:

Some types of calendar available are

Gregorian calendar Julian calendar Islamic calendar Solar Hijri calendar Hebrew calendar

Gregorian calendar: January 1st is new year and it the most widely used calendar in the world.

Julian calendar: January 14th is new year.

Islamic calendar: it follow the phase of the moon and those not regard seasons.

Solar hijri calendar: 21st of March is new year.

Hebrew calendar: 18th September will be the new year for 2020 in the Hebrew calendar.