# Biorhythms and Critical Days — Daily cycle calculator & chart

> Calculate personal biorhythms, critical days, and birth date compatibility. (iPhone/iPad app by Sensortronic.)

- Source: https://appshunter.io/ios/app/biorhythms-and-critical-days/id1486142952 (this page in markdown: same URL + `.md`)
- Developer: [Sensortronic](https://appshunter.io/developer/1486142951)
- Category: Lifestyle, Utilities
- Price: Free
- Rating: 4.70/5 from 320 App Store ratings · 147 written reviews indexed
- Age rating: 4+
- Requires: iOS 15.0 · 26 MB
- Languages: American English
- Released: 2019-11-11
- Data updated: 2026-08-31
- Monetization: ad-supported
- User reviews in markdown: https://appshunter.io/ios/app/biorhythms-and-critical-days/id1486142952/reviews.md

## What is Biorhythms and Critical Days?

Calculate your biorhythms and critical days, and check your birth date compatibility with anyone! Biorhythms is a personal biorhythm calculator and chart covering 8 cycles: physical, emotional, intellectual, intuition, fortune, aesthetic, awareness and spiritual, plus an overall daily rating.

Create up to 10 user profiles, each with its own color theme and daily reminder. The clean, easy to use interface makes your daily biorhythm check quick and effortless. No account and no sign up: your personal data stays on your device.

Features
• Elegant, easy to use interface;
• 8 biorhythm cycles plus an overall daily rating;
• Calculates biorhythms from 2 weeks in the past to 2 months ahead;
• Shows each cycle's daily value for the selected period;
• Shows each cycle's daily trend (rising / declining);
• Daily highlights: a short description and advice for each day;
• Birth date compatibility for any two people;
• Calculates critical days;
• Short, useful advice for each critical day;
• 18 color themes to choose from;
• Personalized color theme for every user profile;
• Personalized daily reminder for every user profile;
• Up to 10 user profiles;
• Available in 8 languages.

Biorhythm theory
Biorhythm theory states that our lives move in predictable undulations, driven by cycles that start at birth and run at a fixed pace. The three classic cycles are:
• Physical, 23 days;
• Emotional, 28 days;
• Intellectual, 33 days.
Beyond the classic three, the app also charts five extended cycles: intuition (38 days), fortune (21 days), aesthetic (43 days), awareness (48 days) and spiritual (53 days).

Critical days
A critical day comes when a cycle crosses the zero line, switching from its high phase to its low phase or back. Such days have been described as days of flux and instability. They are not days when an accident will happen, but days when you may be more accident prone. Simply knowing it is a critical day helps you stay on guard and plan around it.

Privacy notes
• Your personal data (e.g. name and date of birth) is stored locally within your instance of the Biorhythms app only;
• If you uninstall the app, your personal data is deleted completely from your device;
• We do NOT store your personal data on our premises.

## Key features

- Biorhythm calculation
- Critical day identification
- Birth date compatibility
- Multiple user profiles
- Daily highlights and advice
- Customizable themes and reminders

## What do users think of Biorhythms and Critical Days?

Overall sentiment: positive

**Pros**

- 👍 Accurate and helpful
- 👍 Easy to use
- 👍 Detailed information
- 👍 Useful for planning
- 👍 Reliable
- 👍 Interesting and informative
- 👍 Excellent design
- 👍 Comprehensive profiles
- 👍 Compatibility function

**Cons**

- 🐛 Inconsistent data
- 🐛 Buggy critical days feature
- 🐛 Unclear instructions
- 🐛 Poor translations
- 🔍 Cluttered UI with ads
- 🔍 Limited customization options

**Commonly reported bugs**

- Login screen freezes
- Incompatible with older devices
- Incorrect biorhythm calculations
- Overlapping text on mobile screens

**Most requested features**

- Add note-taking functionality
- Expand future/past date range
- Improve color contrast and readability
- Provide more detailed compatibility analysis
- Offer paid ad-free version

## Recent user reviews (10 of 147)

All indexed reviews: https://appshunter.io/ios/app/biorhythms-and-critical-days/id1486142952/reviews.md

### 5/5 — Biorhythms and critical days

*2026-04-19*

This app is so right on! I find things expressed here are very accurate. I am surprised there is such a thing.

Further situations strengthen this! It seems so right on!

### 5/5 — Зачастую совпадает состояние и биоритмы.

*2026-03-24, version 4.4.0*

Прикольное приложение

### 4/5 — Функция

*2026-03-17, version 4.4.0*

Сделать виджет со всеми показателями дня

### 5/5 — для понимания

*2026-02-26, version 4.4.0*

использую для большей уверенности в каких то аспектах принятия решений и в принципе хорошая замена монетке (орел/решка)

### 4/5 — Seems more complete than my other biorhythm app

*2026-02-24, version 4.4.0*

More metrics, not sure about accuracy.

### 5/5 — Отлично

*2026-02-15, version 4.4.0*

Отличное приложение.Все совпадает.Что хорошо,много ритмов и все четко работает

### 5/5 — Great App

*2026-01-29, version 4.4.0*

Accurate and helpful.

### 5/5 — Very Useful

*2026-01-12, version 4.4.0*

I appreciate how easy it is to use this app. Thanks for allowing calculation on multiple people!

### 3/5 — Miss D McCarron

*2025-10-05, version 4.4.0*

The different Physical for example titles are half missing so I can’t read what the later one’s as they don’t fit on My fone screen.   Also is there any instructions of how to use the App properly,  to get the best out of using it?   If these 2 issues were sorted,  I would give more stars & a better review?

### 2/5 — Bad UI with ads

*2025-09-28, version 4.4.0*

It’s a pretty ugly UI/UX, with ads. No way to delete account data either.

## Frequently asked questions about Biorhythms and Critical Days

### What does the Biorhythms and Critical Days app do?

This app calculates your personal biorhythms, which are believed to influence your physical, emotional, and intellectual states. It also identifies critical days, which are periods of potential instability, and assesses birth date compatibility with others.

### What are the key features of this app?

Key features include calculating biorhythms from two weeks in the past to two months in the future, showing daily values and trends for each cycle, identifying critical days with advice, and assessing birth date compatibility. It also supports up to 10 user profiles with personalized themes and reminders.

### How much does the Biorhythms and Critical Days app cost?

The app is free to download and use. It is supported by advertisements, which are displayed within the application.

### What is the Biorhythms Theory?

The Biorhythms Theory posits that human lives are influenced by three main cycles: physical (23 days), emotional (28 days), and intellectual (33 days). These cycles begin at birth and are thought to affect daily life.

### What are critical days and how does the app help with them?

Critical days are identified as times of potential flux and instability, where one might be more prone to accidents or errors. The app highlights these days and provides short, useful advice to help users be more aware and potentially avoid difficulties.

## Version history (last 5 releases)

### 5.0.3 — 2026-08-09

Fixed: the birth date picker was unreadable in the dark theme, showing an empty sheet instead of the date wheels. It now follows the app theme in both light and dark. Thank you to the user who reported it.

### 5.0.2 — 2026-08-08

Biorhythms is back, rebuilt from the ground up for current iPhone and iPad.

- Rebuilt on a modern foundation: faster launch, smoother screens
- All 8 biorhythm cycles plus an overall daily rating
- Redrawn charts, sharp on every screen size
- Compatibility, critical days and per profile reminders all carried over
- Your profiles and birth dates still never leave your device
- New: a consent screen for ads in Europe, with privacy settings in the app menu

Thank you for your patience while the app was rebuilt.

### 5.0.1 — 2026-08-07

Biorhythms is back, rebuilt from the ground up for current iPhone and iPad.

- Rebuilt on a modern foundation: faster launch, smoother screens
- All 8 biorhythm cycles plus an overall daily rating
- Redrawn charts, sharp on every screen size
- Compatibility, critical days and per profile reminders all carried over
- Your profiles and birth dates still never leave your device

Thank you for your patience while the app was rebuilt.

### 4.4.0 — 2021-05-12

Updated to comply iOS 14.0+ transparency policy

### 4.3.1 — 2020-12-06

Improved performance
Minor bug fixes

## Apps similar to Biorhythms and Critical Days

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| --- | --- | --- | --- |
| [BioRhythm Horoscope](https://appshunter.io/ios/app/biorhythm-horoscope/id1321066154) | — | Free | Lifestyle |
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## More apps by Sensortronic

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All apps by Sensortronic: https://appshunter.io/developer/1486142951

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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 2026-08-31.*