Your chart: date, time and place

A chart is like a photo of the sky at the moment you were born. To take that photo, the app needs three things: the day, the time and the place. Each one does its own job.

Where you fill it in

The first time you open the app, tap Calculate my chart. You'll see Your birth details:

• Name (optional).
• Date of birth.
• Time, and right under it, How sure is the time?
• Birthplace: start typing and pick your city from the list.
• Traditional formula: Male or Female.

Then tap Calculate my chart. Everything is worked out on your phone, with no internet.

If your details are already on another phone, tap Scan a QR code on the first screen instead and point the camera at that phone's code. If you have a backup, tap Import a backup.

The date

The date gives you three of your four pillars: the year, the month and the day.

There's one surprise. The BaZi calendar follows the sun, not the calendar on your wall. The year starts at Lì Chūn (立春), the Start of Spring, around February 4. Each month starts on a solar term, somewhere between the 4th and the 8th. So if you were born in late January, your Year pillar may belong to the year before. That's not a mistake. It's the tradition.

The time

The time gives the fourth pillar, the Hour. BaZi splits the day into twelve blocks of two hours, each with its own animal. Most of the time, a few minutes either way change nothing. Near the edge of a block, they can.

The time can matter for the Day pillar too. By default, the app's day starts at 11 pm, not at midnight. So a birth late in the evening already belongs to the next day.

If you're not sure of the time, say so under How sure is the time? You can choose Exact, About ± 15 min, Between… and… or I don't know. The app works with what you give it and marks what depends on the hour. There's a whole article about this in Learn: "If you don't know your exact time".

The place

The place does two quiet jobs.

• It sets the clock. Time zones and daylight saving time have changed many times over the years. The app carries the historical tables, so it knows what the clocks said in your city on that very day. Under the place, you'll see the time zone it used.
• It finds the sun. Noon on the clock isn't always noon by the sun. The app uses your city's true solar time, which depends on how far east or west you are. In some places the gap is more than an hour.

That's why your chart says something like "Born on March 3, 1975 in Lima, at 8:10 by the clock and 7:52 by the sun."

Can't find your town? Pick a larger city nearby. The search uses a city list built into the app, so nothing is sent anywhere.

The traditional formula

Two old formulas ask for a male or a female version: the direction of your ten-year cycles, and your Kua number. That's all this choice changes. It says nothing about who you are.

You pick one of the two; it's required. If someone arrives without it (an older chart saved with both, a QR code or a backup from an earlier version), the app asks you to choose as soon as you open it, one person at a time. Without the formula there are no decades.

When the clocks played tricks

On some nights, clocks went back an hour, and the same time happened twice. On others, they jumped forward, and a time never existed. If your birth falls on one of those, the app asks you.

• That time happened twice: pick the first time, the second, or Not sure, show both.
• That time didn't exist: check the time on the birth certificate.

Changing it later

Nothing is set in stone. Go to People, tap your name and choose Edit details. The chart is recalculated right away.

And if you're curious how it was done, open How we calculated it on the Chart tab. It walks you through each step: the time zone, the moment in UTC, solar time and the position of the sun.