The number nobody prints
Birthday pages are almost always built from a table of date ranges, which can only ever return the name of a sign. The underlying calculation, the Sun's ecliptic longitude, is what an ephemeris records, and reducing it to one of twelve labels throws away most of what it contains.
For this date the longitude is a little over three hundred and thirty two degrees measured from the start of Aries, which is the same thing as two degrees of Pisces. Knowing that lets you say which planets your Sun aspects, where a solar return will fall, and which ten degree band of the sign you occupy.
It also tells you how far the birth fell from the nearest boundary, which is the honest way to answer someone worried about being near a cusp.
Why it hardly changes from year to year
The tropical year runs a little under three hundred and sixty five and a quarter days, so on a common calendar year the Sun's position on a fixed date advances by about a quarter of a degree. The leap day cancels the accumulated shift, pulling the date back by close to a full day.
The result is a repeating sawtooth rather than a steady drift. A birth in a leap year sits near the low end of the window and one three years later sits near the top, and the whole spread stays under a degree and a half.
The century rule trims the remaining error by skipping the leap day in most years divisible by a hundred. Over the span considered here only 2000 was in question and it kept its leap day, so the pattern runs uninterrupted.
The decan, and what tradition attaches to it
Two degrees of Pisces falls in the first decan, the band from zero to ten degrees. In the Chaldean order, which runs the planets by apparent speed continuously around the zodiac, that band is assigned to Saturn even though the sign as a whole answers to Jupiter in the classical scheme and to Neptune in the modern one.
Tradition reads the Saturn band as the most contained part of Pisces, where the sign's openness is given a shape. Competing schemes assign the same ten degrees to Jupiter by following the triplicity of the sign, so the label is convention rather than observation and is best held loosely.
The placements the date cannot reach
The Moon changes sign every two and a half days or so, which means a birth on this date falls in one of two lunar signs depending on the hour, and across different years it has covered all twelve. There is no connection between a calendar date and a Moon sign.
The rising sign is undetermined until a time and a place are known, since it moves through the whole zodiac in a day and rises at very uneven rates depending on latitude. The widget above resolves all of this from your own details and reports the distance from your birth to the nearest sign boundary.
Houses follow the horizon, so an unknown time leaves most of the chart's structure unbuilt even when the Sun is beyond dispute.
Questions people ask about this
What sign is 21 February?
Pisces. The Sun entered the sign a day or two earlier, around 18 or 19 February, so this date is past the change in every year.
How far into Pisces is the Sun?
About two degrees, with a spread of a little over a degree across the last century at noon. Your own year and hour fix it more precisely.
What is the first decan of Pisces?
The first ten degrees of the sign. In the Chaldean sequence it is ruled by Saturn, which is read as the more structured and self contained part of Pisces.
Does the year change the sign?
No. The solar position on a fixed date oscillates within about a degree and a half and never approaches the boundary from here.
Why bother with the degree?
Because aspects, house placement and solar returns all depend on it. The sign name alone cannot produce any of them.
Is my Moon sign Pisces too?
Not necessarily and usually not. The Moon runs through the zodiac in a month, so it can be in any of the twelve signs on this date depending on the year.