astrootldr

Big three calculator

Your Sun, Moon, and rising sign from one form. A birth time is optional: without it, any placement that changed on your birthday is shown hour by hour.

Birth data

Your birth data stays in your browser. Nothing is sent to the server.

Advanced - manual coordinates & offset

How this calculator works

The Sun and Moon positions come from Astronomy Engine and the rising sign from local sidereal time at your birth place. Each placement is checked separately, so a missing time only affects the ones that actually changed on your birth date.

The other planets, the houses, and the aspects are in the full birth chart.

Questions

What is the big three in astrology?
Your Sun sign, Moon sign, and rising sign. The Sun sign is the one most horoscopes use, the Moon sign is where the Moon was at your birth, and the rising sign is the sign on the eastern horizon at that moment.
Which parts of the big three need my birth time?
The Sun changes sign about once a month, so a birth date alone almost always settles it. The Moon changes sign every two to three days, so a date usually settles it too. The rising sign changes every couple of hours and needs the time. Without a time, this calculator shows a single answer where the day allows one and an hourly table where it does not.
Why is my calculated Sun sign different from the dates in a horoscope column?
Sun sign date ranges are rounded averages. The Sun enters each sign at a slightly different moment each year, so people born on the first or last day of a range can belong to the neighboring sign. This calculator uses the Sun's actual position for your date.
Is my birth data saved anywhere?
No. The sign is computed by JavaScript in your browser and nothing is sent to a server. The page link keeps your date and place so you can come back to the result, so share that link only with people you would tell your birthday to.

Reference, not advice

This is cultural and astronomical reference, not personal prediction or advice.

This calculator is a reference tool. Astrology is documented cultural and historical material; it is not a scientifically demonstrated method of prediction. See the disclaimer.

Sources

Last reviewed .