Frequently asked questions
Short answers to the questions people tend to have before and after reading their chart. For the full reasoning behind each rule, see How we calculate your chart; for how your details are handled, see the privacy policy.
I don't know my birth time. Can I still get a reading?
Yes. Choose "I don't know the time" and we leave out the hour pillar and read the other three pillars, six characters in all. The year and month pillars and your Luck Pillar starting age are then worked out from noon: noon Korea Standard Time for births in Korea, noon local clock time for births elsewhere. If you were born on the day a solar term began, your month pillar could go either way, so your result flags it, and your Luck Pillar starting age may be off by about a year. If you find out your birth time later, enter it again to see the hour pillar.
How do I enter a lunar birthday or a leap month?
On the input screen, choose Lunar in the calendar field, enter the date, and tick "It was a leap month" if it was. If that lunar year has a leap month, the screen tells you which month it is, and if you pick a leap month the year doesn't have, it asks you to clear the box. Lunar dates are accepted for 1900–2100, for births in South Korea, North Korea, China, Taiwan, Hong Kong, Macao, Singapore and Malaysia. For births anywhere else, we calculate from the solar date.
Why is my chart different from another BaZi calculator?
Where schools of BaZi disagree, calculators pick different rules, and the same birth details can then produce a different chart. The usual points of difference are how a birth in the 23:00 hour is assigned (the Zi hour), whether the clock gets a true solar time adjustment, what happens when you were born in the very minute a solar term began, how daylight saving time is handled, and whether Luck Pillar ages are counted from birth or the traditional East Asian way. On your result, "See how this was calculated" shows which rules applied to your chart, and if you change an option we tell you which pillars changed.
I was born between 11 pm and 1 am. Which day counts?
With the default single Zi hour, the next day begins at 23:00, so both your day pillar and hour pillar follow the next day. If you switch to Late and early Zi, a birth in the 23:00 hour keeps that day's day pillar, and only the hour pillar follows the next day. Schools disagree on how to split the Zi hour, so we don't treat either option as the right one. With the true solar time adjustment on, the adjusted time decides, so a birth a little after 23:00 on the clock may not fall in the Zi hour at all.
What is the true solar time adjustment, and can I turn it off?
Clock time follows your time zone's standard meridian, not your exact location. Korea Standard Time is set to 135°E, so while that meridian is in use, Seoul's clock has to be moved back about 32 minutes on average to match the Sun. The Sun's meridian crossing also drifts earlier or later through the year, by between about −14 and +16 minutes; that drift is the equation of time. The adjustment works out both from your birthplace's longitude and your birth date, and applies them to the day and hour pillars only. It's on by default, and you can switch it off in your result's calculation options if you want to compare with a calculator that doesn't adjust.
I was born during daylight saving time. Do I need to change anything?
No. Enter the clock time from your birth record exactly as written. We work out from your birth date and place whether daylight saving was in effect and calculate from standard time: our own table covers Korea's daylight saving years (1948–1951, 1955–1960 and 1987–1988), and the IANA time zone history covers everywhere else. If you enter a time that never happened because clocks sprang forward, we read it as standard time; if it happened twice because clocks fell back, we take the daylight saving one. Either way your result flags it.
Does it work if I was born outside Korea?
Yes. Pick "Anywhere else" as your birthplace, then choose your country and city. We read the time you enter as local clock time, look up the standard time and any daylight saving for that place and date, and by default adjust for the city's longitude. Our guide for births outside Korea covers what to do if your city isn't listed, or if the time difference seems to change your birth date.
I was born in January or early February. Why is my year pillar from the year before?
In BaZi the year changes at the exact moment of the Start of Spring, not on January 1 or at Lunar New Year. If you were born before that moment, your year pillar belongs to the previous year. In 2025, for instance, the Start of Spring fell at 23:10 Korean time on February 3, so a baby born in Korea at 9 pm that day has the same year pillar as 2024: 甲辰. If you read your zodiac animal from the year pillar, it moves back a year for the same reason.
Why does my Luck Pillar start one year off from another site?
We count Luck Pillar ages from birth, the way international age works. The starting age comes from the number of days between your birth and the nearest relevant solar term, divided by three, which is time elapsed from zero, just like international age. Calculators that count ages the traditional East Asian way add a year, so the same Luck Pillar can appear one year later in age there. Your result shows how the start year was counted above the Luck Pillar table.
Do you store my birth details?
Your birth date, time, sex and birthplace are used only while the request that builds your chart is being handled, and AevoStar does not store them on its servers. We don't ask for your name, email address or phone number. The "recently viewed" list does stay in the browser you're using, up to 10 entries, and you can delete entries one by one or all at once from the input screen. The usage counts AevoStar collects never include your birth date, birth time or birthplace. The privacy policy has the details.
What does someone see when I send a share link?
A share link carries your birth date and time, calendar type (solar, lunar or leap month), sex, birthplace and calculation options, so whoever opens it sees the same result you do. No name, alias or other identifying information goes into the link. Share pages are set not to be indexed by search engines, but anyone you send the link to can see the result, so check who you're sending it to.
Does compatibility give us a score?
No. There's no overall compatibility score. Instead you see five aspects, each on a three-step scale: your Day Masters, your day branches, the Five Elements, cross-pairs of characters, and your current Luck Pillars. Compatibility is where BaZi schools differ most, so we decided only what to look at and set no weighting or overall verdict. If either person's birth time is unknown, the hour pillar is left out for both.
Can I rely on my reading for important decisions?
Please don't. AevoStar's readings follow traditional BaZi theory and are for entertainment and self-reflection only. They are not medical, legal or financial advice, so talk to a professional before any decision that matters. The same chart can also be read differently by different schools.
What's the difference between the Plain and Detailed views?
They show the same calculation at two depths. Plain, which opens first, sums up your tendencies and current phase in everyday words with no Chinese characters. Detailed shows the chart table, Luck Pillar and yearly tables, the detail tables and the proper terms. The readings in both views are built from the same pieces of text, split up or joined together. Switch between them with the tabs at the top of your result, and in Detailed view, tap any cell of the chart to see what that character means.
BaZi readings draw on traditional theory and are for reference only. Different schools may read the same chart differently.