Why BaZi Calculators Disagree: 6 Tools Tested

Why BaZi Calculators Give Different Charts: 6 Tools, 4 Tricky Birth Times

If you have ever put your birth details into two BaZi calculators and got two different charts, neither site is necessarily broken. Most disagreements come from four places: when the year starts, what happens late at night, daylight saving time, and births outside China.

On 8 October 2026 we entered the same four birth times into six free calculators and wrote down every pillar. One of the six is ours, XuanSeal. That matters for how you read this page, so we say it up front. The test also caught two bugs in our own engine. We fixed them the same day, and the results below show what each tool returned when we tested it.

Quick answer

• We tested only four edge cases, so this is not a measure of how often calculators agree on ordinary birth times.
• Every disagreement we saw came from one of five sources: when the year starts (Li Chun or Chinese New Year), lunar months versus solar-term months, the late Zi hour rule, daylight saving time, and births outside UTC+8 close to a solar-term change.
• MingLi, FreeBaZi.com and EightFates handled all four cases with their default settings. FreeBaZi.com also explains its rules on the page and lets you switch them.
• With default settings, freebazi.geomancy.net gave a chart we consider wrong on three of the four cases: it builds its main chart on lunar months and has no place or time-zone input. Master Sean Chan only removes daylight saving if you tick a box, and once ticked, its header and its pillar table disagree. With true solar time switched off, MingLi and FreeBaZi.com fall back to clock time, which ignores daylight saving.
• If your birth falls into one of these edge cases, check your chart in two calculators and read the settings, not only the pillars.

How we tested

We used four invented birth times, all male (gender only changes the direction of the luck pillars):

We worked out the reference answers before testing. Solar-term moments come from lunar-javascript, an open-source calendar library that our own engine also uses, so the reference is not fully independent of XuanSeal. With default settings, Master Sean Chan, MingLi, FreeBaZi.com and EightFates all matched its year and month pillars in both solar-term cases (A and D). By that library, the 2023 Li Chun moment is 4 February 10:42 Beijing time, which is 02:42 UTC. We used each tool's default settings first. Where a tool offered true solar time, daylight saving or late Zi hour options, we ran it again with those options switched.

We tested Master Sean Chan, MingLi, FreeBaZi.com, freebazi.geomancy.net, EightFates and XuanSeal. Joey Yap's BaZi Plotter asks you to sign in before it draws a chart, so we left it out.

Case A: Chinese New Year is not the start of the BaZi year

Chinese New Year 2023 fell on 22 January, but the BaZi year changes at Li Chun, the start of spring, on 4 February. A baby born on 28 January 2023 is still in the Water Tiger year: 壬寅 year, 癸丑 month, 丙戌 day, 甲午 hour.

Five of the six tools got this right. The exception was freebazi.geomancy.net. Its main chart follows the lunar calendar and shows a 癸卯 Rabbit year and a 甲寅 month. The solar-term version (壬寅, 癸丑) appears only in a smaller table further down. FreeBaZi.com lets you switch the year boundary to Chinese New Year, and doing so reproduces the same 癸卯 answer. That shows the disagreement is a rule choice, and the Li Chun rule is the one used in classical BaZi.

What to check: if you were born in January or early February, make sure your calculator says it uses Li Chun.

Case B: the late Zi hour has two accepted rules

The Zi hour runs from 23:00 to 00:59. Practitioners disagree on whether the day pillar changes at 23:00 or at midnight. Both schools are in use, so both answers count as correct here:

• Day changes at midnight: 丁丑 day, 壬子 hour.
• Day changes at 23:00: 戊寅 day, 壬子 hour.

All six tools returned one of these days. What differed was how open they are about it:

What to check: if you were born between 23:00 and midnight, your day pillar, and with it your Day Master, depends on this rule. Pick a tool that tells you which one it uses.

Case C: daylight saving time and longitude

Madrid was on summer time (UTC+2) in July 1985. The clock said 09:10, but standard time was 08:10. Madrid also lies far west of the meridian its time zone is based on, so true solar time was about 06:50. That gives three possible hour pillars:

• Clock time with nothing corrected: 辛巳. This is wrong, because daylight saving is an administrative shift, not solar time.
• Standard time (daylight saving removed): 庚辰. Defensible for schools that do not use true solar time.
• True solar time: 己卯. The answer after removing daylight saving and correcting for longitude and the equation of time.

MingLi, FreeBaZi.com and EightFates returned 己卯 by default. They look up the birthplace, remove daylight saving and apply true solar time without being asked. With true solar time switched off, MingLi and FreeBaZi.com returned 辛巳: they then use the clock time and do not remove daylight saving on their own. EightFates has no option to switch it off.

Master Sean Chan has a daylight saving checkbox, and it is off by default. With true solar time on (its default) and the box unticked, it returned 庚辰. That matches the standard-time answer, but only because it skipped the one-hour summer shift and then applied the longitude correction. When we ticked the box, the header above the chart said the time had moved to 06:50 and the 卯 hour. The pillar table underneath still showed 庚辰. We reloaded the page and repeated the test three times with the same result.

freebazi.geomancy.net has no place or time-zone input. It only offers two-hour slots, so it returned 辛巳.

XuanSeal: before 8 October our engine did not remove daylight saving time when true solar time was switched off, which is the default. It returned 辛巳. Since the fix it returns 庚辰 with true solar time off and 己卯 with it on.

What to check: if you were born during summer time anywhere, look at the hour your calculator actually used. A one-hour difference changes the hour pillar for roughly half of daylight-saving births.

Case D: births outside China on a solar-term day

Solar-term moments are absolute moments in time. Li Chun 2023 happened at 02:42 UTC. A birth in Madrid at 08:00 local time (07:00 UTC) came after it, so the chart is 癸卯 year, 甲寅 month, 癸巳 day. The hour is 丙辰 by the clock, or 乙卯 by true solar time (about 06:31).

A calculator that compares the Madrid clock time directly with Beijing-time solar terms sees 08:00 as earlier than 10:42 and returns the previous month and year, 壬寅 and 癸丑.

• Master Sean Chan and FreeBaZi.com returned 癸卯 甲寅 with true solar time on or off. EightFates returned 癸卯 甲寅; it has no option to switch true solar time off.
• MingLi returned 癸卯 甲寅 by default. With its "Local Solar Time" option switched off, the birthplace field is greyed out and ignored, and it returned 壬寅 癸丑.
• freebazi.geomancy.net returned 癸卯 甲寅. This is correct, but by coincidence: on that date the lunar month happens to match the solar-term month.
• XuanSeal: before 8 October our engine made this mistake too, whether true solar time was on or off. A Madrid or New York birth in the hours after Li Chun got the previous year and month. Since the fix it returns 癸卯 甲寅.

This case matters more than it looks. Each year has twelve month-changing solar terms. For someone born in New York, the gap between local time and Beijing time is twelve or thirteen hours. So a calculator with this bug gives the wrong month pillar to roughly one or two births in a hundred, and every luck pillar follows from the month pillar.

What to check: if you were born outside China within a day of a solar-term change, compare your month pillar in two calculators that ask for your birthplace.

Results at a glance

Our own row is the one you should trust least, because we wrote this page. Every tool here is free, so you can rerun any case yourself with the birth times in the table above.

How to check your own chart in two minutes

1. Open your chart in two calculators that ask for your birthplace, not only a time zone.
2. Compare the year and month pillars. If they differ, check whether you were born near Li Chun or another solar-term change, and whether one tool follows Chinese New Year.
3. Compare the hour pillar. If it differs, check whether daylight saving time was in effect and whether true solar time is switched on in one tool and off in the other.
4. Compare the day pillar. If it differs and you were born between 23:00 and midnight, check the late Zi hour rule first. Then check whether a daylight-saving or true solar time correction moved the birth across midnight in one of the tools.
5. Decide which rules you accept, then use one tool consistently. Reading a chart from one rule set and luck pillars from another causes more confusion than either rule alone.

FAQ

Which BaZi calculator is the most accurate?

On our four tests, MingLi, FreeBaZi.com and EightFates gave correct charts with their default settings. FreeBaZi.com was the most transparent about its rules. "Most accurate" also depends on which late Zi hour rule and solar-time rule you accept. A good tool tells you which ones it uses.

Should I use true solar time for my BaZi chart?

Many modern practitioners do, especially for births far from the meridian of their time zone, where the correction can exceed an hour. Some schools use standard time instead. Either way, daylight saving time should be removed, because it does not follow the sun.

Why does my Day Master change between calculators?

Usually because you were born between 23:00 and midnight and the tools use different late Zi hour rules. Less often, the hour shift from daylight saving or true solar time pushes the birth across midnight.

Does Chinese New Year change my BaZi year?

No. The BaZi year changes at Li Chun, around 4 February. Chinese New Year belongs to the lunar calendar, which classical BaZi does not use for the pillars.

Next Step

You can run the same checks in the XuanSeal BaZi calculator. Our methodology page lists the exact rules our engine follows. If your chart is new to you, the step-by-step chart reading guide and the hour pillar guide explain what each pillar means. For a broader look at choosing between free tools and paid readings, see how to choose a BaZi calculator or AI reading.

Disclaimer

BaZi is a traditional system for reflection and cultural study. These tests compare each calculator's output with the reference rules set out above, and check whether its output matches what the tool says it does. They say nothing about whether BaZi predicts outcomes. Not medical, legal, financial or mental health advice.