Your lagna is the sign that was rising in the east at the moment you were born. It changes about every two hours, so it depends on the birth time far more than the Moon sign does.
About this page
What this page tells you. Your lagna sign, its degree and nakshatra, and the times that sign began and stopped rising on your birth day at your birth place.
How to read it. Enter the birth details. Check how many minutes separate your birth time from the nearest change: if it is less than the doubt in your birth time, the lagna is not certain.
Good to know: Birth times are often rounded to the nearest five or fifteen minutes. A lagna near either edge can belong to the neighbouring sign.