Gaja Kesari yoga
Gajakesari yoga forms when Jupiter is in a kendra (houses 1, 4, 7 or 10) counted from the Moon. The name refers to the elephant and the lion. This site checks it in the birth chart.
What it is
The standard rule is Jupiter in a kendra from the Moon sign. The yoga is described as giving intelligence, good reputation and a steady temperament, in the traditional readings.
How it is worked out or read
The house is counted from the Moon's sign: the Moon's sign is house 1, and Jupiter's sign is counted from it. The birth chart computes this and states whether the rule is met.
Where it appears on this site
The result is in the birth chart. The Moon chart article explains the reference.
The rule and its reference
Gajakesari yoga forms when Jupiter is in a kendra counted from the Moon. The kendras are the houses one, four, seven and ten counted from the Moon's sign. The name compares the strength of the elephant and the lion, and the traditional readings associate the yoga with intelligence, a good name and a steady temperament. The reference is the Moon, not the Lagna, which is the common error a beginner makes.
This site checks the rule in the birth chart and reports whether Jupiter falls in one of those four houses from the Moon. The check uses the Moon's sign as house one, so the reader can repeat it by hand from the sign table.
Counting by hand
Find the Moon's sign and call it house one. Count forward through the signs until you reach Jupiter's sign, then add one. If the result is one, four, seven or ten, the rule is met. For example, a Moon in Karka with Jupiter in Makara places Jupiter in house seven from the Moon, since Makara is the seventh sign counting Karka as one; a kendra, so the yoga is present.
A reader should do the count twice, once from the Moon and once from the Lagna, to be sure the reference is the one the rule asks for.
What the traditional texts describe
The classical descriptions of Gajakesari are generally favourable, speaking of wisdom, reputation and a lasting position. They are not predictions, and they depend on the strength of Jupiter and the other factors in the chart. A Jupiter that is weak or afflicted in a kendra from the Moon is read as giving a more modest version of the yoga's themes.
Using the yoga without overreach
A yoga present in a chart is a fact about the chart's structure, not a promise. The reader should describe the yoga as a traditional combination whose rule is met, and should note the other factors that shape its expression. The site shows the result with the rule stated, so the reader can see exactly what has been checked.
Gajakesari in a whole chart
Gajakesari is best read alongside the other Moon-based rules, since it uses the Moon as its reference. A chart with the Moon in a strong position and Jupiter in a kendra from it is read as more fully expressing the yoga's themes. The reader should also check Jupiter's own dignity and aspects, because a yoga whose main planet is weak gives a more limited picture.