Free tools
Astrology Tools
Seventeen small calculators, each answering one question from your birth data, with the old astrology behind it. They run in your browser, with no sign-up.
About the day you were born
What the sky looked like on your birthday.
Your lots
Points counted from the Sun, the Moon and your rising degree. They need your birth time.
Timing
Which years matter, from the cycles the old astrologers watched.
Points of the Moon's orbit
The Nodes and Lilith: three points on the Moon's path that move by date.
Which zodiac
Why a Vedic chart can show a different sign.
No birth time?
What still holds when you don't know the hour.
How these tools are made
Every tool here runs in your browser. There is nothing to install and no sign-up. Each one answers one question, and each sits beside an article that explains the answer from the old texts.
The positions. They come from four places. The first is Astronomy Engine, an open-source astronomy library. The daemon calculator runs it in your browser; for the Moon phase, North Node, weekday, Saturn return, midlife transit and birth day tools I used it in advance to build tables: every New Moon from 1920 to 2031 to the minute, every sign change of the true North Node, Saturn and the outer planets every ten days from 1920 to 2090. The second is the set of formulas in Jean Meeus, Astronomical Algorithms (2nd ed., 1998), used for the Part of Fortune, lunar mansion, solar return, sidereal and Lilith tools. The third is the Swiss Ephemeris star catalogue, for the positions of the fixed stars, carried forward to your birth year. The fourth is for the planets in the fixed star finder: orbital elements from NASA's Jet Propulsion Laboratory (Standish), corrected against Astronomy Engine.
How close they are. Where a tool was checked against a full ephemeris, this is how close it came:
- Daemon: tested against the Swiss Ephemeris on charts from 1953 to 2024, within a hundredth of a degree.
- Part of Fortune: 380 random births checked against Astronomy Engine, largest difference 0.01 degree.
- Lunar mansions: 3,000 dates checked against an independent ephemeris, largest difference 0.015 degree, and against the mansion times in Warnock's tables.
- Fixed stars: planets within 0.06 degree.
- Sidereal finder: the Sun within one minute of arc.
- Solar return: the moment lands within about five minutes.
- Moon phase: all 1,387 New Moons checked against an independent ephemeris, within 0.8 minutes, 17 seconds on average.
- Saturn return: 400 random birth dates checked against the full ephemeris, dates within a day.
- Lilith: checked against the Swiss Ephemeris mean apogee dates.
- North Node: sign changes agree with published true node tables to within about an hour.
Your birth time matters more than any of these. The rising degree moves about one degree every four minutes, so a time rounded to the hour can shift your houses and lots more than the arithmetic ever will.
The zodiac and the houses. All the tools use the tropical zodiac (the sidereal finder shows the Lahiri sign beside it): the signs counted from the March equinox, as Ptolemy argued they should be. Houses are whole signs: your rising sign is the 1st house, the next sign the 2nd, and so on, the system the Hellenistic sources used.
Dates covered. Weekday, Moon phase and North Node: 1920 to 2031. Daemon: 1900 to 2031. Saturn return, midlife transits, profection year, lunar mansion, fixed star and sidereal finders: births 1920 to 2026. Part of Fortune, Lilith and solar return: births 1920 to 2015, with solar returns up to 2035. Birth day checker: 1925 to 2015.
Your data. The calculations run on your device. Your full birth date and time are not sent anywhere. Two things do leave the page: the daemon calculator sends the town you type to a free place lookup service (Open-Meteo) to get its coordinates and time zone, and the site keeps an anonymous count of page views and tool use, with a short result such as the sign or house found, or the birth year for the Saturn return and midlife tools. No cookies, and IP addresses are not saved (privacy notice).
The books behind them
The numbers come from astronomy. What they mean comes from the old astrologers, read in the translations named on each page.
- Claudius Ptolemy, Tetrabiblos (2nd century): which planets belong to the day and the night (weekday), the natures of the fixed stars, the Part of Fortune, the ages of life (Saturn return, midlife transits), the tropical zodiac, the rising degree (birth day checker), the Good Daemon (daemon).
- Vettius Valens, Anthology (2nd century): the Part of Fortune and the daemon, profection years, the solar return, Saturn's period and the transits that work hardest, finding the rising sign.
- Dorotheus of Sidon, Carmen Astrologicum (1st century): profections and the revolution of the year, the slow Moon (Lilith), the Part of Fortune and the Lot of Religion (daemon).
- Paulus Alexandrinus, Introductory Matters (4th century): the rule for profections, the lots and his own worked example (Part of Fortune, daemon).
- Firmicus Maternus, Mathesis (4th century): the bright and regal stars (fixed stars), the Lot of Fortune and the Part of the Daemon.
- William Lilly, Christian Astrology (1647): the fixed stars and their degrees, and his table of strength for the Part of Fortune.
- Abu Ma'shar, On the Revolutions of the Years of Nativities: how to read the solar return.
- Agrippa, Three Books of Occult Philosophy (1533): the uses of the 28 mansions, the Behenian stars, the threefold daemon.
- The Picatrix (11th century), in Christopher Warnock's Mansions of the Moon: the names and images of each lunar mansion.
- And two stories older than any of these: Cassius Dio on the order of the week (weekday), and Aristophanes on Hekate's supper (Moon phase).
Common questions
How accurate are these calculators? To about a hundredth of a degree for the daemon and the Part of Fortune, and within a tenth of a degree for the lunar mansion, fixed star and sidereal tools. Times are close to the minute for New Moons, within about five minutes for solar returns and within about an hour for the North Node's sign changes. The figures are listed on this page. A birth time rounded to the hour is a bigger source of error than the calculation.
Why does another site give me a different result? Usually because of the zodiac, the house system or the version of a point. These tools use the tropical zodiac and whole-sign houses; a sidereal site will put most placements one sign back, and a site using another house system can move a planet to the next house. The North Node can be true or mean, and Lilith mean or true, and they can differ near a sign change. Each tool page says which one it uses.
Do I need my birth time? Not for most of them. The weekday, Saturn return, midlife transits, profection year, North Node and Lilith tools need only your birth date. The Part of Fortune, daemon and solar return need your birth time and place. If you don't know your time, start with the birth day checker.
Are the tools free? Yes. No sign-up and no email. If you want your whole chart read, that is what the readings are for.