How often the two meet
A conjunction is a shared ecliptic longitude, read here with an orb of eight degrees. Mars circles the zodiac in about twenty two and a half months and Saturn in roughly twenty nine and a half years, so Mars catches Saturn about every two years. That is the synodic period of the pair, and it is short enough that the conjunction is a familiar event rather than a rare one.
Occasionally Mars turns retrograde close to Saturn and passes over the same degrees three times across several months. Those triple conjunctions produce a longer than usual window and have historically attracted extra attention, which is a fact about the history of astrology rather than about the sky.
Because Saturn moves so slowly, the conjunction happens in a different sign each time and works its way around the zodiac over decades. Where it fell in a given year is easy to look up and easy to verify, which is more than can be said for what it means.
The two malefics in one place
In the older classification Mars is the lesser malefic and Saturn the greater. Mars signifies cutting, heat, competition and the willingness to act. Saturn signifies cold, time, limit and the weight of consequence. They are opposites in the physical scheme the tradition used, which is why the pairing has such a heavy reputation in texts written before the modern period.
A conjunction fuses. It does not put the two in dialogue or grind them against each other; it makes a single mixed signature out of them. The standard descriptions are effort that meets resistance from within, patience that has an edge to it, and a capacity for sustained hard work that the person concerned rarely finds enjoyable.
Modern practice usually softens the old verdict, reading the conjunction as discipline applied to force rather than force defeated by discipline. Both readings are in circulation. This site is not going to declare either one correct, but it is worth knowing that a source calling this aspect simply unfortunate is following a particular tradition rather than reporting a fact.
Sign, dignity and house
Sign changes a great deal here because both bodies have strong preferences. In Capricorn, Saturn rules and Mars is traditionally exalted, so the conjunction is read as concentrated and effective rather than obstructed. In Cancer, Saturn is in detriment and Mars in fall, and the same conjunction reads as effort that cannot find its footing. Those are the two extremes and most charts sit somewhere between them.
House decides where the whole thing operates. In the sixth it reads as work and health. In the tenth it reads as career and reputation. In the fourth it reads as family ground and the conditions you started from. Since houses depend on birth time, an approximate time leaves this open.
Anything else touching the same degrees will reshape the reading again. A benefic in aspect to the conjunction, or a strong ruler, is exactly the sort of detail that separates one chart with this aspect from another.
Orb, generations and what to check
Saturn holds a narrow band of degrees for months at a time, so everyone born in a stretch of weeks shares roughly the same Saturn. That means this conjunction is partly a generational marker: a cohort of births carries it, and what individuates them is the house position and the rest of the chart. Reading it as a purely personal signature overstates it.
Orb still does the heavy lifting. Inside one degree the conjunction is a genuine chart theme and the descriptions above are worth taking seriously. Between five and eight degrees it is a background factor. A conjunction spanning a sign boundary is weaker again, since the two are then operating under different rulers.
The check above reports the exact separation, both signs, the house and the retrograde status of each body. Given how loaded this pairing is in the older literature, having the actual numbers in front of you is the best defence against reading more into it than is there.
Questions people ask about this
How often does Mars conjunct Saturn?
About every two years, which is the synodic period of the pair. Mars needs roughly twenty two and a half months to lap the zodiac while Saturn barely moves, so it catches up on a fairly regular schedule.
Is Mars conjunct Saturn a difficult aspect?
Traditional astrology classed both as malefics and read the conjunction unfavourably. Modern practice more often reads it as discipline applied to drive. Neither reading is settled fact, and sign, dignity and house shift the interpretation considerably.
What is a triple conjunction?
When Mars turns retrograde near Saturn it can cross the same degrees three times over several months, conjoining, retreating and conjoining again. It does not change the natal aspect for someone born under it, but it makes the transit period unusually long.
Does the sign make much difference?
A great deal. In Capricorn, Saturn rules and Mars is exalted, which the tradition reads as the pairing working well. In Cancer, Saturn is in detriment and Mars in fall, which it reads as the pairing working badly. Most charts fall between those poles.
Is this aspect generational?
Partly. Saturn stays within a few degrees for months, so everyone born in that stretch shares it. What makes it personal is the house it falls in, which depends on birth time, and whatever else in the chart aspects those degrees.
What orb should I use?
Eight degrees is the conjunction orb on this site. Inside one or two degrees the aspect is strong enough to build a reading around. Out past five it is a supporting detail rather than a theme.