If asked when does Lent begin, many people will be prompt to answer that this 40 day period begins on Ash Wednesday and some would even add that it ends with Easter Sunday. This invariably means that you need to know Easter Sunday date to find out the date on which the Lent season begins in a particular year.
Ash Wednesday is considered to be the first day of Lent, and therefore its date is determined on the basis of Easter date. Basically, Lent, Ash Wednesday, Mardi Gras and Good Friday dates are calculated on the basis of Easter date which is, in turn, calculated in accordance to the Lunisolar calendar.
According to the Holy Bible, these 40 days represent the time which Jesus spent in the desert before the beginning of his public ministry. Within the season of Lent, there exist several holy days - including the Ash Wednesday (i.e. the first day of Lent), the Palm Sunday (marks the beginning of the Holy Week), Maundy Thursday (a day Christians commemorate the Last Supper) and Good Friday (commemorating the crucifixion of Jesus Christ). Easter Sunday is a significant day to celebrate his resurrection.
According to the Lunisolar calendar, which determines the date for Easter celebrations, Easter Sunday falls on 1st April in 2018. If we go by the belief that Lent begins with Ash Wednesday - which falls 40 weekdays or 46 days before Easter Sunday, it will begin on 14th February, 2018.
So the season of Lent will begin on 14th February (Ash Wednesday) and end on 31st of March (Holy Saturday) in 2018. Similarly, Mardi Gras - which is celebrated a day before the Lent season begins, will fall on 13th of February in 2018, Maundy Thursday on 29th March and Good Friday on 30th March, 2018.
If you know the date on which Easter Sunday falls according to the Lunisolar calendar, you can easily calculate the date for Ash Wednesday - which happens to be the beginning of Lent.