Piday

PiDay is the nerdiest calendar app ever made.

Every day, PiDay opens to today and shows you exactly where that date appears in the first five billion decimal digits of pi. Search for your birthday, an anniversary, or any date you care about, then see where it lives in infinity.

PiDay searches multiple date formats and highlights the best match, so you can explore your date from different calendar conventions and compare where each one appears.

Features:

Find today’s date in pi instantly
Search birthdays, anniversaries, and any other date
See the exact position where a date appears
Compare multiple date formats
Explore a calendar heat map of how early dates appear
Save favorite dates
Share your discoveries as cards
Personalize the app with multiple themes
Works on iPhone, iPad, and Mac
PiDay keeps things simple:

No accounts
No ads
No tracking
A decade worth of bundled dates, or search any string using a live lookup service for dates outside the bundled range.

If you’ve ever wondered whether your birthday is hiding in pi, this is the app for you. Show More