Planet positions come from a real ephemeris, with houses and the Ascendant calculated from your birth place and its historical time zone — the same engine behind ChartCast episodes.
Or explore a sign’s archetype chart
Or open a sign’s full page — chart, reading and a ready-to-play episode — from the twelve zodiac signs.
The free chart tool gives every chart its own link — calculate it once, copy the address and whoever opens it sees the same wheel and reading.
The tropical dates the Sun enters each sign, with its element, modality and ruling planet. Cusp births drift by about a day each year — calculate the chart above if yours falls on a boundary.
| Sign | Dates | Element | Modality | Ruling planet |
|---|---|---|---|---|
| Aries | March 21 – April 19 | Fire | Cardinal | Mars |
| Taurus | April 20 – May 20 | Earth | Fixed | Venus |
| Gemini | May 21 – June 20 | Air | Mutable | Mercury |
| Cancer | June 21 – July 22 | Water | Cardinal | Moon |
| Leo | July 23 – August 22 | Fire | Fixed | Sun |
| Virgo | August 23 – September 22 | Earth | Mutable | Mercury |
| Libra | September 23 – October 22 | Air | Cardinal | Venus |
| Scorpio | October 23 – November 21 | Water | Fixed | Pluto |
| Sagittarius | November 22 – December 21 | Fire | Mutable | Jupiter |
| Capricorn | December 22 – January 19 | Earth | Cardinal | Saturn |
| Aquarius | January 20 – February 18 | Air | Fixed | Uranus |
| Pisces | February 19 – March 20 | Water | Mutable | Neptune |
A birth chart calculator takes a birth date, time and place and works out where every planet stood in the sky at that moment. This one uses a real ephemeris (astronomy-engine, VSOP87/ELP) rather than lookup tables, so positions are accurate to about an arc-minute, and it draws the house cusps, Ascendant and Midheaven from the birth coordinates and the historical time zone in force on that date.
Yes. Calculating a chart, seeing the wheel, the placements table and the full written reading is free and needs no account. A ChartCast account is only needed if you want to save charts or turn them into podcast episodes.
Tick “I don't know the time” and the chart is cast for noon. The signs of the Sun, Mercury, Venus, Mars and the outer planets stay reliable, and so do most aspects. The Moon can shift up to about six degrees across a day, and the Ascendant, Midheaven and all house placements are not usable without a time.
In the tropical zodiac the Sun moves through Aries from about March 21, Taurus April 20, Gemini May 21, Cancer June 21, Leo July 23, Virgo August 23, Libra September 23, Scorpio October 23, Sagittarius November 22, Capricorn December 22, Aquarius January 20 and Pisces February 19. The boundaries drift by roughly a day from year to year, so if you were born within a day of a cusp only a calculated chart settles which sign your Sun is actually in.
Two reasons. Cusp births fall on a boundary that moves each year, so a fixed date table gets them wrong. And sidereal (Vedic) astrology uses a different reference frame — with the Lahiri ayanamsa most Sun signs land roughly one sign earlier. This calculator uses the tropical zodiac, the western standard.
Placidus, the most widely used system in western astrology, calculated from the true semi-arc, with a Porphyry fallback at extreme latitudes where Placidus breaks down. Aspects use conventional orbs for the major angles.
No. The calculation runs and the result is returned to your browser. Nothing is written to a database unless you create an account and save a chart yourself.
New each week: how to read a chart in the right order, rising sign vs sun sign, stelliums, unknown birth times and more.