Colorful Birthday defines a symbolic and systematic way to assign a color identity to every birthday and to discover colorful connections between dates across the year.
It transforms the traditional idea of a birth date into a colorful, cyclic system of time — linking months, numbers, and meaning.
Every person’s birthday belongs to one of four primary color groups, inspired by the CMYK color model, representing four emotional and seasonal stages of the year.
| Month Range | Assigned Color | Birthday Type | Meaning |
|---|---|---|---|
| January – March | Cyan | Cyan Birthday | Freshness, clarity, beginnings |
| April – June | Magenta | Magenta Birthday | Emotion, creativity, expression |
| July – September | Yellow | Yellow Birthday | Energy, warmth, growth |
| October – December | Black | Black Birthday | Depth, reflection, completion |
Each birth month defines the base color of a person’s Colorful Birthday Identity.
In addition to the main birthday color, each person also has a set of Colorful Birthdays — symbolic dates throughout the year that “resonate” with their original date of birth.
A date is considered a Colorful Birthday if its month and day numbers together contain both digits of the person’s birth date (month and day), regardless of order.
If multiple dates in the same month meet this condition, only the first matching day of that month is recognized as the Colorful Birthday.
In other words, a Colorful Birthday reflects a numerical resonance between the original birth date and other dates in the calendar.
The digits of one’s birth month and day reappear — sometimes in reversed order — across the months of the year, forming a sequence of symbolic color echoes.
Only the earliest occurrence per month is kept to ensure simplicity and uniqueness.
function getColor($month){
switch ($month) {
case 1:case 2:case 3: return "Cyan Birthday";
case 4:case 5:case 6: return "Magenta Birthday";
case 7:case 8:case 9: return "Yellow Birthday";
case 10:case 11:case 12: return "Black Birthday";
default: return "Invalid Birthday";
}
}
function getColorfulBirthdays($month, $day){
$birthdays = [];
for($i=1; $i<=12; $i++){
for($j=1; $j<=getDaysInMonth($i); $j++){
if(
(str_contains((string)$month, (string)$i) && str_contains((string)$day, (string)$j))
||
(str_contains((string)$month, (string)$j) && str_contains((string)$day, (string)$i))
){
$birthdays["$i-$j"] = getColor($month);
break; // First matching day per month
}
}
}
return $birthdays;
}
function getDaysInMonth($month) {
// Return number of days in given month
}
The Colorful Birthday Standard is published under a dual license model:
You are free to use, remix, and share both — with proper attribution to
© 2025 — The Colorful Birthday Project.