See the current planetary hour and the day's 24 hours for your city, computed from the real sunrise and sunset.
Planetary hours split the day, from sunrise to sunset, into 12 equal parts, and the night, from sunset to the next sunrise, into another 12. Because day length changes through the year and with latitude, these hours almost never last 60 minutes. Each one is ruled by one of the seven classical planets, in Chaldean order, starting with the planet of the weekday. The tool computes sunrise and sunset with the Astronomy Engine library for the city and date you pick, shows the current hour with a countdown and the full table, and exports the day as .ics.
In traditional astrology and magic, the planetary day runs from sunrise to sunset and the planetary night from sunset to the next sunrise. Each of these periods is divided into 12 parts equal to one another, called planetary hours. Since day and night are rarely the same length, day hours and night hours differ in duration, and both change from one day to the next. Near the equinoxes they come close to 60 minutes; at the June solstice in London, the day hour lasts more than 83 minutes and the night hour less than 37.
Each hour has a ruling planet. The order is Chaldean, from the planet with the slowest apparent motion to the fastest: Saturn, Jupiter, Mars, Sun, Venus, Mercury and Moon, then it starts over. The first hour of the day belongs to the planet that names the day: Sun on Sunday, Moon on Monday, Mars on Tuesday, Mercury on Wednesday, Jupiter on Thursday, Venus on Friday and Saturn on Saturday.
On Sunday the sequence of rulers is Sun, Venus, Mercury, Moon, Saturn, Jupiter and Mars, repeated through the 24 hours. Since 24 divided by 7 leaves a remainder of 3, the first hour of the next day advances three places in the Chaldean order: after 24 hours starting at the Sun, hour 25 falls on the Moon. This rule produces the order of the days (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn) and explains why Sunday, Monday and Saturday are named the way they are in many languages.
A checked example: on Friday, October 23, 2026, in Sao Paulo, the first hour is Venus and the sequence continues Mercury, Moon, Saturn, Jupiter, Mars and Sun; hour 8 is Venus again, and so are hours 15 and 22. The tool's table agrees with a published table for that day to within a minute per hour.
Sunrise and sunset come from Astronomy Engine: the instant the Sun, with standard atmospheric refraction, has its center 0.833 degrees below the horizon, which equals the upper limb of the disk touching the horizon. The calculation assumes a flat horizon at sea level. Mountains, buildings and local terrain are not included, so the real Sun may show up a few minutes later or vanish earlier.
In Sao Paulo, on October 23, 2026, the Sun rises at 05:27 and sets at 18:15: the day hour lasts 64 minutes and 1 second, and the night hour 55 minutes and 55 seconds. The time zone comes from the chosen city, with daylight saving rules from your browser's time zone database. For a place not in the list, enter latitude, longitude and time zone in Options.
Above the polar circle (about 66.5 degrees of latitude) there are days when the Sun does not set and days when it does not rise, and Sun-based planetary hours cease to exist. In Longyearbyen, Norway (78.2 degrees north), this holds for June 21 and December 21, 2026. In those cases the tool warns you and uses 06:00 and 18:00 local clock time as an approximation, without pretending it follows the Sun. In the transition weeks, a day can have a sunrise and sunset with very long or very short hours, and the table shows that normally.
In the tradition each ruler is linked to certain subjects: Sun to success, authority and health; Moon to intuition, family and short trips; Mars to courage, sport and conflict; Mercury to study, communication and trade; Jupiter to expansion, law and money; Venus to love, art and friendship; Saturn to discipline, limits and long-term tasks. The Highlight hours for option marks in the table the hours tied to a subject.
These are cultural associations repeated for centuries, not measured results: there is no scientific evidence that doing something in a particular planetary hour changes the outcome. Use it as a way to organize your time, if that works for you.
Paste the code into your HTML and the tool shows up on your page, without J-Kit's navigation and ads. It still runs in the browser of whoever visits your site.
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src="https://jkit.tools/embed/en-US/planetary-hours-calculator"
width="100%"
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></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
They are 24 divisions of the astrological day: 12 between sunrise and sunset and 12 between sunset and the next sunrise. Each hour is ruled by a classical planet (Saturn, Jupiter, Mars, Sun, Venus, Mercury or Moon), in a fixed sequence that starts with the planet of the weekday.