Pregnancy

Ovulation Predictor Calculator

Built by Kevin Glover · @gloverbuilds · Verified formula

Predict ovulation day and fertile window from cycle length. Free ovulation predictor.

📅 Updated April 2026 ✅ Formula verified 📖 4 min read 🆓 Free · No sign-up

In this article

How to Use This Calculator
Getting Accurate Results

Methoden

Kalender: Eisprung ~14 Tage VOR naechster Periode. LH-Tests: zuverlaessiger. Basaltemperatur: bestaetigt im Nachhinein. NFP (Natuerliche Familienplanung) ist in Deutschland weit verbreitet.

Fruchtbares Fenster

5 Tage vor bis 1 Tag nach Eisprung. 1-2 Tage vor Eisprung: hoechste Wahrscheinlichkeit.

⚡ CalcWolf Insight

The most common fertility timing mistake: waiting for a positive OPK to have intercourse. By then, the best 2-3 days are already ending. Start every-other-day intercourse 5 days before expected ovulation. Treat the OPK as confirmation, not a starting signal.

Frequently asked questions

Wann am fruchtbarsten?▾

1-2 Tage vor Eisprung.

LH-Tests noetig?▾

Praeziser als Kalender. Ab ~2 € pro Test bei dm/Rossmann.

✓ Math logic verified against primary sources → See our verification process

Kevin Glover · @gloverbuilds

Founder, CalcWolf · GLVTS · Blickr

All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →