A position, not just a name
A sign is a thirty degree stretch of the ecliptic, and saying someone is a Leo only says which stretch the Sun occupied. The finer measurement is the degree inside that stretch, and it is the number an astrologer would actually work from.
On 29 July, taken at noon and across every year from 1930 to 2035, the Sun has fallen between roughly five and a half and just under seven degrees of Leo. That is a small window. The leap year cycle keeps the calendar aligned with the orbit, so the same date returns to nearly the same solar position year after year, with the four year pattern shuffling it slightly and then pulling it back.
Six degrees is a long way from any boundary
The Sun left Cancer about six days earlier and will not reach Virgo for another three and a half weeks. There is no year in the modern era, and no hour of the day, in which a 29 July birth produces anything other than Leo.
That matters because the doubt people feel about their sign usually comes from dates published as ranges. A range has to round, and rounding is what makes 22 July or 23 August contentious. Six degrees inside the sign is well past the reach of any rounding, so this date can be stated flatly.
People are sometimes told that a birth in the first days of a sign is a weak or diluted version of it. Nothing in the technical scheme supports that. A Sun at six degrees is in Leo exactly as fully as one at twenty six, and the degree affects which aspects it forms rather than whether the sign applies.
The first ten degree band
Each sign divides into three bands of ten degrees, called decans, and a position near six degrees falls in the first of them. In the Chaldean sequence, the one that runs the planets in order of apparent speed, that opening band of Leo is assigned to Saturn.
The pairing is an odd one on paper, since Saturn governs the sign opposite Leo, and the older texts read the combination as warmth held under restraint: showmanship with a spine of discipline behind it, ambition that shows itself slowly. That reading is a convention inherited from the tradition rather than an observation, and it should be weighed as such. What is not a convention is which band the position falls in, since that follows straight from the degree.
What the date will not tell you
The Moon travels roughly thirteen degrees a day, so on any 29 July it occupies one sign in the morning and can be in the next before the day ends. Two people who share this birthday can easily have Moons in different signs, and the date alone cannot separate them.
The rising sign moves faster still, turning through all twelve signs in a day and shifting with the latitude of the birthplace. A date fixes one placement out of dozens. The widget above takes a year, an hour and a place, returns the exact solar degree rather than the century wide band, and reports how far the birth stood from the nearest sign boundary.
Read that way, a birthday is a real but modest piece of information. It fixes one body, narrows its position to a small band and names the decan, and it is silent about the parts of a chart that vary between two people born on the same afternoon.
Questions people ask about this
Is 29 July always Leo?
Yes. The Sun is around six degrees into the sign, roughly a week after it left Cancer, so no year and no birth hour changes the answer. The variation across a century is a fraction of a degree either side of that figure.
What degree is the Sun on 29 July?
Between about five and a half and just under seven degrees of Leo at noon, depending on the year. Your own year and birth time narrow it to a single figure, which the widget above returns.
Which decan does this birthday fall in?
The first, which covers the opening ten degrees of Leo. The Chaldean order gives that band to Saturn, a pairing the older texts read as display tempered by restraint.
Why does the degree hardly change from year to year?
Because the leap day resets the drift. Three years of quarter day slippage push the date slightly later against the Sun, and the added day in February pulls it back, so the position circles a fixed point.
Does a birth time change the sun sign here?
No. The Sun covers about one degree in a full day, so the difference between a midnight birth and a late evening one is well under a degree and cannot move the sign or the decan.
What still needs a birth time?
The Moon often does, since it can change sign inside a single day. The rising sign and the house placements always do, because they depend on the exact clock time and on the latitude of the birthplace.