BBT Chart - Simple Fertility
1-second log, biphasic chart
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
Record basal body temperature and view it in a clear graph, keeping day-to-day fertility tracking easy to review.
BBT Chart is a simple, lightweight fertility log dedicated to one thing: a digital version of the paper basal body temperature sheet, plus automatic interpretation.
■ One-second morning log
The entry screen opens instantly, with the picker preset to your last value - nudge it and tap Save. Includes ±0.01 fine-tune buttons, period-start marks, one-line notes, and a daily 7:00 reminder (changeable).
■ A biphasic chart you can trust
Line charts are generated per cycle. The thermal shift is detected by a clear, documented rule (3-over-6: three consecutive days above the highest of your previous six readings), and the coverline uses that same maximum. The rule is spelled out inside the app, so you always know why a line was drawn. Short gaps of 2-3 days are bridged with dashes; longer gaps are left honest.
■ Ovulation estimate & cycle stats
The day before the shift is shown as the estimated ovulation day. Average cycle length and luteal-phase length over the last six cycles are computed automatically.
■ Print layout for clinic visits
Preview a clean A4 white-background table (date, cycle day, temperature, period, notes) you can show your gynecologist as-is.
■ CSV export
Take your data anywhere as CSV (Excel-ready, UTF-8 with BOM).
■ Built for peace of mind
- Fully local: data stays on your device. No account, no server
- No analytics SDK; your records are never sent to the ad SDK
- Atomic writes - designed above all so records never vanish
- Deliberately no Bluetooth thermometer sync (no sync failures, ever)
■ Pricing
Unlimited history, charts, shift detection, cycle stats, printing, and CSV are all free. "Remove Ads" ($0.99 one-time, no auto-renewal) only hides the banner ad.
■ Disclaimer
This app provides general reference information only. It does not diagnose pregnancy or provide contraception guidance. Please consult your gynecologist.
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The developer, 丽佳 施, 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 Used to Track You
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- Identifiers
Data Linked to You
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Accessibility
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Information
- Seller
- 丽佳 施
- Size
- 5 MB
- Category
- Lifestyle
- 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+
- Contains
Advertising
- In-App Purchases
Yes
- Remove Ads $0.99
- Copyright
- © 2026 Jayden Chen