What is actually happening in the sky
Saturn orbits the Sun once in about twenty nine and a half years. Seen from Earth it works its way round the zodiac in that same span, so it passes any given degree once per lap. The second return is simply the second time it reaches the exact degree and sign it held at your birth.
Nothing about the second crossing is astronomically different from the first. It is the same body arriving at the same point on the ecliptic, and the widget above finds it the same way, by tracking Saturn's real position rather than adding an average to your birth date.
The gap between the first return and the second is one whole orbit, so anyone who has had a first return already knows roughly how far ahead the second sits. What they cannot know without calculating is the exact date, because the interval is not a flat twenty nine years.
Why fifty eight is only an approximation
Planetary orbits are ellipses, not circles, and a body moves faster when it is closer to the Sun. Saturn therefore covers some stretches of the zodiac more quickly than others, and how long it takes to come back to a particular degree depends on which degree that is.
Over one lap the spread is around twenty eight to thirty one years. Doubled, it becomes wider still, so second returns turn up anywhere from about fifty six to a little past sixty two. Quoting fifty nine as the age is an average of that range rather than a date, which is why the calculator above works from the actual crossings.
The passes and how long the span runs
Saturn is retrograde for roughly four and a half months of every year. When a return falls near one of those stationary points, Saturn crosses your natal degree, reverses back over it, then goes forward across it a third time. Three passes spread over nine months to a year is the ordinary outcome, and a single clean pass happens only when the timing sits well clear of the retrograde.
The tradition does not pick one of those dates as the event. It reads the whole span, from the first crossing to the last, as one period. The widget above lists every pass with its date so you can see which case you have.
Passes matter more here than most descriptions admit. A three pass return covers most of a year, which is a period rather than a day, and a one pass return is over almost before it registers. Those are quite different things to be told you are having.
How it is read, and what makes it specific
Saturn is conventionally read as structure, obligation and the accumulated consequences of how a life has actually been arranged. A second return is described as that review arriving with far more behind it than the first, often around retirement, changed health or shifting responsibility for other people. The promise attached to it in the tradition is a settled sense of what is worth carrying forward. The difficulty attached to it is that some things get put down whether or not you meant to put them down. Both are convention rather than finding, and neither predicts anything about your particular life.
What makes a reading specific is the house holding your natal Saturn, since the same return is interpreted quite differently in the sixth than in the eleventh. That needs a birth time. The dates do not, because Saturn shifts so little in a day that the degree is effectively fixed.
Questions people ask about this
At what age is the second Saturn return?
Usually fifty eight or fifty nine, though the real range runs from around fifty six to just past sixty two. The variation comes from Saturn's elliptical orbit and from where your own natal Saturn sits within it.
Is the second return the same as the first?
Astronomically yes, it is Saturn reaching the identical degree one more lap on. The tradition reads it differently only because of what has usually accumulated in the intervening thirty years.
How many passes will mine have?
Either one or three, depending on whether the crossing falls near a retrograde period. Three is the more common outcome, and the calculator above shows each date so you can see the full span.
Do I need a birth time?
Not for the dates. You need one for the house placement, and the house is what turns a general description into something specific to your chart.
Is there a third Saturn return?
Yes, at roughly eighty seven to eighty nine for those who reach it. It is the same cycle continuing, and it is calculated in exactly the same way.
Should I expect something to happen on the date?
This page does not predict events, and no date on the chart obliges anything. What it gives you is the crossings, the length of the span and the house involved, which are the checkable parts.