Hoffmann SoftwareBiorhythm & Family Planning
Cycle calendar and an experimental family-planning model from the original program.
FREE · NO SIGN-UP · ONLINE
Cycle calendar and an experimental family-planning model from the original program.
Choose an analysis
If you choose, your birth dates and cycle details will appear automatically on future visits. The chart will start from today each time.
I explicitly agree to save my birth dates and cycle information in a browser cookie on this device for 180 days.
Birth dates and menstrual data are private. The cookie is set only with your agreement, sent only to this calculator, and can be erased at any time. No profile database.
The âgirlâ curve averages the man's emotional and intuitive cycles; âboyâ averages his physical and intellectual cycles. The combined curve includes both partners.
The search checks the next estimated ovulation on which a model curve is higher. The fertile window spans the five preceding days plus ovulation day. This cannot predict a babyâs sex.
Traditional biorhythm theory is not scientifically validated. Sex prediction has no proven predictive power. Calendar-based ovulation estimates are unreliable and must not be used for contraception or medical planning.
Ovulation is estimated at about 14 days before the next period. The five preceding days and the estimated ovulation day are highlighted as a possible fertile window. Actual ovulation may differ.
The experimental boy/girl curves use the manâs biorhythm and are shown alongside the womanâs cycle. They do not predict a babyâs sex, and the calendar is not reliable contraception.