Should I use the due date or the date of birth?

Once your baby is born, use the date of birth: that is the date the sign goes by. Before the birth, the due date gives a first guess, and the calculator shows every sign and month that is possible if your baby arrives up to two weeks early or late.

What does born on the cusp mean?

It means born on the day the Sun moves from one sign into the next. The exact moment changes a little from year to year, so on these days the sign depends on the year, the time and the place of birth.

Why do websites give slightly different dates for the signs?

The Sun enters each sign at a slightly different time every year, and tables round that to whole days in different ways. A difference of one day at the edge of a sign is normal.

Why do some months have more than one birthstone?

Jewellers have added alternatives over the years, so each month has stones in different colours and prices. June, for example, has pearl, alexandrite and moonstone. Any of them counts as the birthstone.

Does a star sign say anything about my baby's personality?

No. There is no scientific evidence that the sign someone is born under shapes who they become. Enjoy it as a tradition, like a family story told at birthdays.

Baby zodiac sign, birthstone and birth flower

How the sun sign is worked out

Western astrology divides the Sun's yearly path across the sky into 12 equal signs of 30 degrees each. The count starts at the March equinox, the day the Sun crosses the celestial equator heading north, which marks the first day of Aries. Because it is tied to the equinoxes and solstices, this system is called the tropical zodiac: it follows the seasons rather than the stars.

When people say "my sign", they mean the sun sign: the sign the Sun was in on the day they were born. These are the usual dates:

Sign	Usual dates	Element
Aries	21 March to 19 April	Fire
Taurus	20 April to 20 May	Earth
Gemini	21 May to 20 June	Air
Cancer	21 June to 22 July	Water
Leo	23 July to 22 August	Fire
Virgo	23 August to 22 September	Earth
Libra	23 September to 22 October	Air
Scorpio	23 October to 21 November	Water
Sagittarius	22 November to 21 December	Fire
Capricorn	22 December to 19 January	Earth
Aquarius	20 January to 18 February	Air
Pisces	19 February to 20 March	Water

Born on the cusp

The Sun does not enter a new sign at the same moment every year. A year is about 365 and a quarter days long, so the change drifts by a few hours each year until a leap day pulls it back. In most recent years, for example, the March equinox has fallen on 20 March, one day before the date in the table.

That is why the calculator flags the first and last day of each sign as a cusp. For a baby born on one of those days, the exact sign depends on the year, the time of birth and the time zone. If it matters to you, an astrologer or an online birth chart can work it out from the exact time and place.

Due date or date of birth

If your baby is not here yet, the due date gives you a first idea. Only about 1 baby in 25 arrives on the due date itself, and most are born in the two weeks before or after it. So when you choose the due date, the calculator also looks at those four weeks and lists every sign and every month your baby could end up with.

Birthstones and birth flowers by month

The modern birthstone list goes back to 1912, when the American National Association of Jewelers (now Jewelers of America) agreed on stones for each month. It has been updated a few times since: tanzanite joined December in 2002, and spinel joined August in 2016. The calculator uses the list published by the American Gem Society.

Birth flowers are a looser tradition, popular in Britain and North America, and the lists vary from one source to another. The calculator uses the one given by The Old Farmer's Almanac, with the main flower first.

Month	Birthstones	Birth flowers
January	Garnet	Carnation, snowdrop
February	Amethyst	Violet, primrose
March	Aquamarine, bloodstone	Daffodil
April	Diamond	Daisy, sweet pea
May	Emerald	Lily of the valley, hawthorn
June	Pearl, alexandrite, moonstone	Rose, honeysuckle
July	Ruby	Larkspur, water lily
August	Peridot, sardonyx, spinel	Gladiolus, poppy
September	Sapphire	Aster, morning glory
October	Opal, tourmaline	Marigold, cosmos
November	Topaz, citrine	Chrysanthemum
December	Tanzanite, turquoise, zircon	Narcissus, holly

A worked example

Your baby is due on 22 July. In the table that is the last day of Cancer, so the result shows Cancer with a cusp note: in some years the Sun moves into Leo during that day. July's birthstone is ruby and its birth flowers are larkspur and water lily.

Two weeks either side of the due date runs from 8 July to 5 August. Within that window your baby could be a Cancer or a Leo, with July's ruby or one of August's three stones: peridot, sardonyx or spinel.

Signs, stars and science

Astrology is a tradition, not a science. Studies have not found that the sign someone is born under shapes their character, their health or their future. The signs no longer even line up with the constellations they are named after: Earth's axis slowly wobbles, and over the last 2,000 years the signs have drifted by almost a whole constellation. The Sun also passes through a 13th constellation, Ophiuchus, which has no sign.

None of that has to spoil the fun. A birthstone can make a lovely first piece of jewellery, and a birth flower is a sweet detail for a nursery print or a birth announcement. Your child's personality, though, will be all their own.

Baby zodiac sign and birthstone