Planetary Hours Calculator

The Planetary Hours Calculator divides each day into planetary hours and tells you which of the seven classical planets, the Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn, rules each hour. Based on the ancient system of horas used in electional astrology, it computes the rulership sequence for your chosen date and location so you can time activities to align with the energy traditionally attributed to each planet.

Planetary hours are not 60 minutes long. The system splits the time from sunrise to sunset into twelve equal daytime hours and the time from sunset to the next sunrise into twelve equal nighttime hours, so the length of each hour shifts with the seasons and your latitude. The first hour of the day is ruled by the planet that governs that weekday (the Sun rules Sunday, the Moon Monday, and so on), and the rest follow the fixed Chaldean order of the planets.

Practitioners use planetary hours to choose timing for specific intentions: a Venus hour for love or art, a Mercury hour for communication and study, a Jupiter hour for growth and finance, or a Mars hour for action and courage. The tool is commonly paired with the auspicious dates finder, where you first pick a favorable day and then drill into the best hour, giving electional astrology two layers of precision.

For accurate results, provide the correct date, location, and time zone, since planetary hours depend on local sunrise and sunset times. Match your activity to the ruling planet you want to emphasize, and remember that nighttime hours follow their own twelve-part division, so the best hour for a given purpose may fall after dark depending on the day.