The question "why does my Vedic horoscope give a different sign" has an exact answer, and it is measured in degrees. The gap between the two systems is called the ayanamsa, and for 2026 it comes to 24°13'43" by Swiss Ephemeris. Below is where that number comes from, the full sidereal date table for 2026, and how many people actually change sign.
Two starting points
Western astrology uses the tropical zodiac. Zero degrees Aries is the spring equinox, the moment the Sun crosses the celestial equator. The sign is tied to the season, not to the stars.
Vedic astrology uses the sidereal zodiac, anchored to the fixed stars. Zero Aries there is defined by the position of the stellar background.
The problem is that these two points drift apart. Earth's axis traces a cone over roughly 25,800 years, and because of that precession the equinox point creeps backwards through the zodiac at about 50 arcseconds a year. Two thousand years ago the two zeros coincided. Today twenty-four degrees separate them.
How the ayanamsa has grown
- 1900: 22°28'17"
- 1925: 22°48'43"
- 1950: 23°09'53"
- 1975: 23°31'06"
- 2000: 23°51'33"
- 2026: 24°13'43"
- 2050: 24°33'56"
One degree every seventy-two years. In practice the sidereal sign boundaries shift by about a day over two generations: your grandmother's sidereal dates were a day earlier than yours.
Sidereal sign dates for 2026
Computed with the Lahiri ayanamsa, the official one in India. Compare them with the tropical dates you know from magazine horoscopes.
- Capricorn: 14 January to 11 February (tropical: 21 December to 19 January)
- Aquarius: 12 February to 13 March (20 January to 17 February)
- Pisces: 14 March to 13 April (18 February to 19 March)
- Aries: 14 April to 14 May (20 March to 19 April)
- Taurus: 15 May to 14 June (20 April to 20 May)
- Gemini: 15 June to 15 July (21 May to 20 June)
- Cancer: 16 July to 16 August (21 June to 21 July)
- Leo: 17 August to 16 September (22 July to 22 August)
- Virgo: 17 September to 16 October (23 August to 22 September)
- Libra: 17 October to 15 November (23 September to 22 October)
- Scorpio: 16 November to 15 December (23 October to 21 November)
- Sagittarius: 16 December to 13 January (22 November to 20 December)
On boundary dates the exact time matters: the Sun enters sidereal Aries on 14 April at 04:06 UTC, so someone born the same day at two in the morning is still a Pisces. The shift is 23 to 25 days throughout. Here is a check on specific dates, computed separately: someone born on 10 August 2026 is a Leo in the Western system (Sun at 17°53' Leo) and a Cancer in the Vedic one (23°40' Cancer). Someone born on 20 August is a Leo in both: 27°30' tropical, 3°16' sidereal.
How many people change sign
This can be computed exactly. A sign spans 30 degrees, the shift is 24.23 degrees, so the fraction of the zodiac that lands in a different sign is 24.23 divided by 30, which is 80.8%.
Four people in five have a different Sun sign in a Vedic chart than in a Western one, and almost always the previous sign. The ones who keep their sign are those born in the last six days of their tropical sign.
There is more than one ayanamsa, and they disagree
Lahiri is not the only one. Here are the five most common, computed for 15 June 2026.
- Fagan-Bradley: 25°06'43"
- Lahiri: 24°13'43"
- Krishnamurti: 24°07'55"
- Raman: 22°46'57"
- Djwhal Khul: 20°24'51"
The spread between the extremes is 4.7 degrees, which is almost five days of solar motion. So two Vedic sites can perfectly well hand you different signs, and neither is wrong: they are simply using different ayanamsas. When two results disagree, the first thing to check is which ayanamsa is set.
What else differs besides the dates
The ayanamsa is the most visible difference, but not the only one.
- Houses. Vedic practice is usually whole sign: one house equals one sign. Western practice is dominated by Placidus with unequal houses.
- Planets. Classical Vedic astrology works with the seven visible planets plus Rahu and Ketu. Uranus, Neptune and Pluto are not part of it.
- Forecasting. The main tool is the dashas, planetary periods, rather than transits.
- The Moon outranks the Sun. The Moon sign and its nakshatra carry more weight than the solar sign.
Because of that last point, the question "what is my Vedic sign" is often not about the Sun at all. Jyotish describes a person primarily by the Moon.
In short
The difference between the systems is the ayanamsa: 24°13'43" for 2026, growing by roughly a degree every seventy-two years. It gives 80.8% of people a different Sun sign in a Vedic chart, usually the previous one. Five common ayanamsas disagree by up to 4.7 degrees, so before comparing two calculations, check which one was used.
You can compute your tropical natal chart free on AstroWay, and sidereal positions with nakshatras are available as a separate calculation.