The narrowest of the major angles
A sextile is sixty degrees with an orb of five, half the latitude given to a conjunction. That ten degree window takes Mars and Jupiter about three weeks to cross at their average relative speed of just under half a degree a day.
Two sextiles occur in each two and a quarter year cycle, one either side of the conjunction, so between them they cover about six weeks of births per cycle. It is a common configuration in absolute terms and a slight one in effect, which is a combination worth holding in mind.
Signs sixty degrees apart belong to compatible elements, fire with air or earth with water. That compatibility carries a fair share of what the sextile is credited with, and it is honest to say so.
Offered, not given
Mars is the acting part of the chart, the initiative and the effort. Jupiter is the widening: more scope, more nerve, a readiness to assume the opportunity is bigger than it looks. A sextile links them without fusing them and without pressure.
What the tradition describes is straightforward: the person can raise their effort when the situation calls for it, and the situation obligingly calls for it fairly often. There is nothing dramatic about it. It is the kind of aspect noticed in retrospect, when somebody works out that a run of things going reasonably well was not entirely accidental.
The catch is that a sextile has to be picked up. Unlike a trine, which the tradition treats as already in the account, a sextile is an offer, and offers are declined all the time by charts that had every capacity to accept.
Orb, house and proportion
Five degrees is not much room and strength drops away fast inside it. A sextile at four degrees is close to negligible. At half a degree it is a real feature of the chart. The check above returns the figure, which is the single most useful thing to know about your version.
House placement needs a birth time and is where the aspect becomes specific. In the sixth and eighth this reads as competence with work and with other people's resources. In the ninth and eleventh it reads as movement, contacts and getting invited into things. The general account is nearly weightless until it is anchored.
Keep it in proportion. If this is the only Mars to Jupiter contact in a chart it is worth a sentence. If the chart also has a tight square from Saturn to Mars, the square is the story and the sextile is where the relief comes from.
Cohort, retrograde and the honest limit
Everyone born in the same three week band shares this aspect. That is a large group of people whose lives have nothing else in common, and the fact is not a reason to ignore the aspect but it is a reason not to inflate it.
Jupiter is retrograde for around four months a year and Mars for roughly two months in every two, so retrograde placements are the ordinary case rather than a complication. A Mars station inside the window can produce more than one exact pass, which is the only timing detail here that carries any weight.
The site's approach throughout is to state the geometry, which is checkable, and then say what the tradition reads into it, which is not. This aspect is a good example of a case where the geometry is unremarkable and the reading should be modest to match.
Questions people ask about this
Why does a sextile use a smaller orb?
By long convention the smaller angles are given less latitude, so a sextile gets five degrees against the seven for a square or trine and the eight for a conjunction. The effect falls away quickly across that range, so a four degree sextile is very faint.
How is this different from Mars trine Jupiter?
Both are read as cooperative, but a trine is treated as capacity already present while a sextile is treated as capacity offered. The practical difference is that a sextile needs a deliberate move to come to anything and often does not receive one.
How often does Mars sextile Jupiter occur?
Twice in each two and a quarter year cycle between the pair, once on either side of the conjunction. Each pass holds for about three weeks at the five degree orb, so the two together cover roughly six weeks of births per cycle.
Do I need a birth time?
Not to detect the aspect, since both bodies move slowly enough for the date to settle it. You do need one for the houses, and without them the reading stays at the level of a whole cohort of births rather than a person.
Is a retrograde Mars or Jupiter a problem here?
No. Jupiter is retrograde about four months a year and Mars roughly two months every two years, so retrograde placements are common and unremarkable. A Mars station near the sextile can produce more than one exact pass, which is the only detail worth noting.
How much weight should I give this aspect?
Modest weight. It is a supportive note shared by a broad cohort, easily outranked by any tighter contact to the same Mars. Read it as where a chart finds a bit of ease, not as a description of the life.