Basal Body Temperature (BBT) / Ovulation Tracker

About the Basal Body Temperature (BBT) / Ovulation Tracker

This BBT Ovulation Tracker helps you log daily basal body temperature (°C/°F) and apply a standard Fertility Awareness Method (FAM) rule to identify the post-ovulation thermal shift. The tool draws a coverline slightly above your pre-ovulatory baseline and looks for three consecutive high temperatures above that line to estimate a retrospective ovulation day and the fertile window.

Use consistent waking temperature readings, taken at the same time each morning, before getting out of bed. Combine BBT with LH tests and cervical mucus observations for better cycle insight. Switch between °C/°F anytime; the tracker also supports optional cycle length and LMP context.

Educational only — not medical advice, diagnosis, contraception, or fertility treatment guidance.

FAQ

• How does the BBT tracker estimate ovulation?
  It draws a coverline above your pre-ovulatory baseline and detects three consecutive highs above that line. Ovulation is estimated retrospectively as the day before the first high.
• How many BBT readings do I need?
  Aim for at least 7–10 consecutive mornings. The rule typically needs six prior days to place a coverline plus three highs.
• Does BBT predict or only confirm ovulation?
  BBT confirms ovulation after it happens. For prediction, combine BBT with cycle history, LH tests, and cervical mucus.
• What exactly is the coverline?
  A reference line slightly above your pre-ovulatory temps. A common rule is the highest of the previous six temps + ~0.05 °C (~0.09 °F).
• What counts as a “high” temperature?
  A post-ovulatory reading that is clearly above the coverline. The tracker checks for three consecutive highs to confirm a sustained shift.
• What affects BBT accuracy?
  Illness, alcohol, poor sleep, shift work, travel, measuring at different times, or getting up before measuring can all alter readings.
• Can irregular or anovulatory cycles prevent detection?
  Yes. Inconsistent rhythms or anovulatory cycles may not show a clear thermal shift. Keep logging and consider LH tests and other signs.
• When should I take a pregnancy test?
  Many test around the expected period or ~10–14 days after the estimated ovulation. Follow test instructions and consult a clinician as needed.
• Is BBT reliable for contraception by itself?
  No. BBT is retrospective. Do not use this tool alone for contraception. Discuss options with a qualified clinician.
• Can I track in °C and °F?
  Yes. You can switch units anytime; values are stored consistently and re-rendered in the unit you choose.

Disclaimer

For education only. Not for diagnosis, contraception, or treatment decisions.

References

• American College of Obstetricians and Gynecologists (ACOG) – Fertility Awareness and Basal Body Temperature Tracking
• Mayo Clinic – Basal Body Temperature Method for Ovulation Tracking
• National Health Service (NHS) – Ovulation Methods and Fertility Signs
• Centers for Disease Control and Prevention (CDC) – Reproductive Health and Fertility
• Barron ML, Fehring RJ. (2005) – Basal Body Temperature Recordings in Fertility Awareness-Based Methods — Journal of Obstetric, Gynecologic & Neonatal Nursing
• Bauman JE. (1981) – Basal Body Temperature: Unreliable Method of Ovulation Detection? — Fertility and Sterility
• World Health Organization (WHO) – Fertility Awareness and Natural Family Planning Methods