☾ Cycle Phase Identifier
Identify your current menstrual cycle phase, energy levels, and get custom recommendations for today.
✦ Today's Recommendations
Workout recommendation
Cognitive Focus →Nutrition focus
Cognitive Focus →Sync to Your Cycle
Get personalized daily workouts, cycle tracking, and custom nutrition plans matching your current phase inside the Moona Web App.
Start Free AI Coaching ✦🧬 How the Menstrual Cycle Impacts Your Fitness
Your menstrual cycle is divided into four main phases, each characterized by fluctuating levels of estrogen and progesterone. These hormonal shifts directly influence your body's energy expenditure, insulin sensitivity, muscle recovery, and joint laxity.
✦ Can I exercise during my period (Menstrual Phase)? ↓
Yes, light training is highly beneficial. Movement triggers blood flow which can significantly reduce menstrual cramps and low back pain. However, avoid high-intensity workouts if you feel fatigued, and swap compound heavy lifts for restorative yoga or zone 2 walking.
✦ Why is the Follicular Phase the best time for muscle building? ↓
Estrogen peaks during this phase, promoting energy, stamina, and anabolic muscle growth. Estrogen also enhances insulin sensitivity, meaning your body uses carbohydrates much more efficiently to fuel intense workouts and repair muscle tissue.
✦ Should I change my diet depending on the phase? ↓
Absolutely. During the luteal phase, your basal metabolic rate increases, which causes natural hunger and cravings. Feeding your body with magnesium and complex carbs keeps insulin levels stable, preventing PMS energy crashes and cravings.
✦ How do hormones change across the four phases? ↓
During menstruation, both estrogen and progesterone are at their lowest. In the follicular phase, estrogen climbs steadily, peaking just before ovulation alongside a surge in luteinizing hormone (LH). After ovulation, progesterone becomes the dominant hormone throughout the luteal phase, then drops sharply if conception doesn't occur — triggering the next period.
✦ Does cycle syncing work for women on hormonal birth control? ↓
Hormonal contraceptives suppress natural ovulation and flatten the estrogen-progesterone curve. If you're on the pill, patch, or hormonal IUD, the four-phase model doesn't apply in the same way. You can still benefit from periodized training — just use weekly training blocks rather than cycle-phase blocks.
✦ What's the difference between cycle length and period length? ↓
Cycle length is counted from the first day of one period to the first day of the next — typically 21–35 days. Period length is just the bleeding portion, usually 3–7 days. The calculator uses both values: cycle length to map phases, and period length to determine when menstruation ends and the follicular phase begins.
📖 How to Use This Calculator
Enter the first day of your last period and your average cycle length. If you're unsure about cycle length, 28 days is the standard default — but tracking 3–6 cycles gives a more accurate personal average.
Results update instantly after you fill in all fields. Compare your current day number against the four-phase breakdown to see where you stand hormonally and what training style fits best today.
📊 Understanding Your Results
The calculator maps your current day to one of four phases: menstrual (days 1–5), follicular (days 6–13), ovulatory (days 14–16), or luteal (days 17–28). Each phase carries a distinct hormonal profile that affects energy, strength, and recovery capacity.
Energy level is estimated from average estrogen and progesterone curves. Real-world energy depends on sleep quality, nutrition, and stress — use the index as a starting reference, not an absolute measure.
⚕️ When to See a Doctor
Consult a gynecologist if your cycle is consistently shorter than 21 days or longer than 35 days, if you experience severe pain that limits daily activities, or if you notice sudden changes in cycle length after years of regularity. Irregular cycles can signal thyroid dysfunction, PCOS, or other endocrine conditions that benefit from early diagnosis.