Peak Flow Log: Asthma Diary
Zones, reliever log & PDF
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
Log your peak flow in seconds and instantly see your green, yellow or red zone from your personal best. Offline, private, one-time purchase.
Peak Flow Log turns your daily peak-flow reading into a clear picture you and your doctor can act on.
Blow into your own peak-flow meter, type in the number, and the app instantly shows your zone as a percentage of your personal best:
- GREEN, YELLOW or RED at a glance, based on your own numbers
- Log reliever (rescue) inhaler puffs, symptoms and triggers in one tap
- See your trend over time with clear color-coded zone bands
- Track more than one person, so parents can follow their child too
- Create a clean PDF report to share at every appointment
Built to be trustworthy:
- Works fully offline. No account, no sign-in.
- Your data stays on your device. Nothing is uploaded.
- Export and import a backup so you never lose your history when changing phones.
- One-time purchase to unlock Pro. No subscription.
Free to log and see your zones. Pro unlocks the doctor PDF, unlimited profiles, full 90-day and all-time trends, and custom zone thresholds.
Peak Flow Log records and visualizes readings you take with your own meter. It does not diagnose, treat, or provide medical advice, and it is not a medical device. Zones are based on a percentage of your personal best that you or your clinician set. Always follow the asthma action plan given by your doctor, and seek medical help in an emergency.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Yoshifumi Sato, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Yoshifumi Sato
- Size
- 2 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English and Japanese
- Age Rating
4+
- 4+
- Copyright
- © 2026 Peak Flow Log