How karana is calculated

A karana is half a tithi — six degrees of elongation — so a lunar month holds sixty of them.

Sixty half-tithis, eleven names. The asymmetry looks arbitrary until you do the arithmetic, and then it is the only arrangement that works.

The arithmetic

Seven of the eleven are movable: Bava, Balava, Kaulava, Taitila, Gara, Vanija and Vishti. They cycle in order, and the cycle repeats eight times. Seven times eight is fifty-six.

That leaves four. Those are the fixed karanas — Shakuni, Chatushpada, Naga and Kimstughna — and each appears exactly once in the month, clustered around the new moon.

Fifty-six plus four is sixty. The seven-and-four split is not a convention laid on top of the month; it is what you get when you ask which repeating cycle fits sixty slots with a remainder small enough to name individually.

Vishti

Vishti, also called Bhadra, is the one most people have heard of, because it is avoided for beginnings. It comes round eight times a month like the other movable karanas, so roughly every three and a half days some part of the day carries it.

What an almanac prints

Panchangam books give karana with its ending time. Daily tear-off sheets usually omit it. Since a karana is half a tithi, its ending times are the tithi boundaries plus the midpoints, so nothing is lost that cannot be recovered from the tithi line.