How Green Flags works
Green Flags is a free, English-language color and compatibility calculator for entertainment. No account is required.
Your profile color
Enter your own birthday and six traits. The day and month map to a hue around a 366-day color wheel. Your answers adjust hue, saturation and lightness, producing a six-digit RGB HEX color. The birth year is used for age comparisons, not the color.
Comparing two people
The calendar wheel shows birthdays. The swatches show profile colors after trait adjustments. Similar and opposite hues describe positions on the color wheel; they do not establish romantic compatibility.
The matching score is a weighted, playful rule: opposite answers score highest, middle-distance answers score halfway, and identical answers score lowest. Daily rhythm follows the same rule: early bird plus night owl receives the highest rhythm score. Opposite birth months also receive a bonus. These are design choices, not scientific findings.
Public profiles
The current catalogue has 1,272 people. Published birthdays are sourced from Wikidata through a public QLever mirror. Full Gregorian birth dates are used; ambiguous matches were excluded. The selection is not an exhaustive list of popular artists. Public-figure traits are simulated and do not describe those people.
Download birthday sources ยท Download the artist coverage check. Data was collected and expanded in October 2026. Wikidata structured data is available under CC0.
Limits
This tool cannot predict healthy offspring, genetic compatibility, fertility, medical outcomes or the success of a relationship. Manually entered profiles use the traits you provide.