# Piday — Mathemagical Calendar

> Calendar app showing dates within the first five billion digits of pi. (iPhone/iPad app by Erik Veland.)

- Source: https://appshunter.io/ios/app/piday/id6760696150 (this page in markdown: same URL + `.md`)
- Developer: [Erik Veland](https://appshunter.io/developer/1833854400)
- Category: Education, Productivity
- Price: Free
- Rating: 5.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 17.0 · 46 MB
- Languages: English
- Released: 2026-03-26
- Data updated: 2026-06-27
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/piday/id6760696150/reviews.md

## What is 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.

## Key features

- Find today's date in pi
- Search for any date in pi
- See exact position of dates
- Compare multiple date formats
- Explore calendar heat map
- Save favorite dates
- Share discoveries as cards

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/piday/id6760696150/reviews.md

### 5/5 — Very clever.

*2026-05-01*

Fun and educational.

## Frequently asked questions about Piday

### What is Piday?

Piday is a calendar application that shows you where any given date appears within the first five billion decimal digits of pi. It helps you explore the mathematical sequence of pi in a unique and engaging way.

### How does Piday work?

You can search for specific dates, such as birthdays or anniversaries, and Piday will display their exact position within the digits of pi. It also highlights today's date in pi automatically upon opening the app.

### Can I search for any date in Piday?

Yes, Piday allows you to search for any date you care about. It searches multiple date formats to find the best match and shows you where it lives in the infinite digits of pi.

### Does Piday have ads?

No, Piday does not have ads. The app is designed to be a clean and uninterrupted experience for users interested in exploring pi.

### What devices does Piday support?

Piday is available on iPhone, iPad, and Mac. It is designed to work seamlessly across these Apple devices.

### Is Piday free to use?

Yes, Piday is completely free to download and use. There are no in-app purchases or subscriptions required.

### How often is Piday updated?

The latest version of Piday is 1.3 (kim), which was last updated on April 29, 2026. Updates typically include improvements and new features.

### What is the age rating for Piday?

Piday has an age rating of 4+, making it suitable for a wide range of users interested in educational and mathematical content.

## Version history (last 2 releases)

### 1.3 (kim) — 2026-04-29

What’s New (1.3 - kim)
Non-pi dates use a DDMM or MMDD format to ensure dates are found in these. Celebrations got an upgrade: featured-day popups + confetti now work for Tau Day (6/28), Euler’s Number Day (2/7), Golden Ratio Day (1/6), and World Quantum Day (4/14). Plus a handful of small fixes and polish.

### 1.0 — 2026-03-26

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-27.*