If today is march 3 in earth what day. Is in mars ?

Trying to assign earth and human values to a different planet is incredibly foolhardy.  If there WAS intelligent life on mars it could organize itself quite differently.  Even if there was not, our ideas of time and day conform to the motion of the EARTH. Mars has different orbits and rotations and times.

As I answer tis question it is not 3rd March but 4th March where I am and 5th March in places to the east of me.

There is no need for a Martian calendar as there are no humans living on Mars. Events on Mars such as the landing pf Perseverance are dated according to our earthly Gregorian calendar.

25th Adir 219 in the Darian Defrost Calendar.

Today is March 3 in certain parts of the world (in others it has already passed midnight into March 4) because in 1582 humans made modifications to the Julian calendar to standardize the year to 365.2425 days.

It is completely arbitrary, there is no reason for it to be that day beyond tradition making it easier to share a standard worldwide calendar. And humans don't exist on Mars, so there is no one there to create a calendar and determine what day it is.

However, if we were to design a calendar for Mars (e.g. in the future when humans attempt to set up a colony) it would be nothing like our Gregorian calendar because the solar year on Mars lasts 687 days. They would either need to add another 11 months or make each of the months last nearly twice as long.

And months themselves would be more tricky as well, since our usage of 12 months in a year is loosely based of the fact that our moon orbits the Earth once every 27.322 days but Mars has 2 moons which orbit at a drastically faster rate than our moon (Phobos takes just 7.66 hours to complete an orbit of Mars while Deimos completes it in 30.35 hours).

So the easiest thing to do would be to just ignore the Martian orbital cycles and just force them to use the standard Earth calendar, most likely on Houston time since that is the NASA standard.

Today is not March 3d on all of the Earth.Right now in Tokyo, it's just past 4 AM of the 4th.

There is no specific to Mars calendar.

gleerp sol the 49 th . 

Mars doesn't have its own calendar (that we know of) because no humans are there.

Technically, it is always at least two different days on earth and occasionally three. On Mars, 'seasons' are longer or there are more of them because it takes 687 days to orbit the sun, (one solar 'year'), rather than 365 days like on earth. 

Nobody has gotten around to naming them, (that I am aware of). Calling them 'months' would make no sense since this is derived from our word for 'moon' (originally one 'moon-th'). Mars has two of those which could get dicey as a comparable standard of measurement. 

Time keeping hasn't been defined up there yet... there's no need for it quite yet. 

Mars has no one living on it, it has no calendar, no months, no weeks, no days of the month, no time of day.

If and when Mars has a permanent colony, they may, or may not, design their own calendar. Or they may stick with the earth one. In the first case, have to wait unit that calendar has been designed. In the latter case, March 3.