Cycle Calendar

Track your menstrual cycle visually. Enter your cycle details and see a color-coded 3-month calendar with predicted periods, fertile windows, and ovulation dates.

Cycle Calendar Input

First Day of Last Period

Average Cycle Length (days)

Average Period Duration (days)

How to Use the Cycle Calendar

Enter Your Cycle Details

Input the first day of your last period, your average cycle length (typically 21-40 days), and how many days your period usually lasts (2-10 days). Click "Update Calendar" to generate your visual cycle tracker.

Read the Color Coded Calendar

Your calendar spans three months with each day color-coded. Purple marks predicted period days, light pink shows the fertile window around ovulation, and light green highlights lower-fertility days. Today is outlined with a bold border.

Plan Ahead

Use the predicted dates listed below each month to plan your schedule. The calendar shows predicted period start and end dates, plus your estimated ovulation date for each month view.

Understanding Your Cycle Phases Visually

Menstrual Phase (Period Days)

Shown in purple. This is the bleeding phase, typically lasting 3-7 days. The lining of your uterus sheds and exits through the vagina.

Fertile Window

Shown in light pink. Usually spans the 5 days before ovulation and the day of ovulation. This is when pregnancy is most likely if you have unprotected intercourse.

Safe Days (Lower Fertility)

Shown in light green. These represent days outside your fertile window and period. While lower-fertility, they are not guaranteed safe for avoiding pregnancy.

Ovulation Day

The day an egg is released, typically around the middle of your cycle. It is highlighted within the fertile window and noted below each month on the calendar.

Tips for Accurate Tracking

✓Mark the first day of your bleeding each month — not the last day — as your cycle start date.
✓Update your average cycle length if you notice changes over time. A running average gives better predictions.
✓Keep a record of at least 3-6 cycles before relying on predictions for planning purposes.
✓If your cycle is irregular, the calendar provides estimates only. Consider combining with other tracking methods like basal body temperature or cervical mucus observation.
✓Use the calendar as a planning aid, not a contraceptive. For reliable birth control, consult a healthcare professional.

Frequently Asked Questions

How accurate are period predictions?

Period predictions are estimates based on your average cycle length and duration. For women with very regular cycles (within 1-2 days), predictions can be fairly accurate — typically within a few days of your actual period start. For those with irregular cycles, predictions may vary significantly month to month. The more cycle data you enter (especially from multiple months), the more reliable the calendar estimates become. Always treat the calendar as a guide rather than an absolute prediction.

Can I use this calendar for family planning?

The cycle calendar can serve as a supplementary tool for family planning by giving you a visual overview of predicted fertile windows and period dates. However, the calendar alone is not a reliable form of birth control. The fertility awareness method requires careful daily tracking of multiple signs (temperature, cervical mucus, cervical position) for effectiveness. If you are trying to conceive or are seeking reliable contraception, please consult a healthcare professional for personalized guidance.

What if my period is late?

A late period can happen for many reasons — stress, illness, changes in weight, travel, hormonal fluctuations, or early pregnancy. If your period is more than a week late from the predicted date, consider taking a pregnancy test if pregnancy is possible. Update the calendar with the new actual start date once your period begins, so future predictions adjust accordingly. Consistently late or absent periods may warrant a visit to your healthcare provider.

How do I track irregular cycles?

Tracking irregular cycles requires a longer observation period and more frequent updates. Start by logging each period's first day and duration for at least 6 months. Calculate your average cycle length from this data and enter it into the calendar. Because irregular cycles can vary widely, use the calendar predictions more as a general guide than a precise schedule. If your cycles vary by more than 7-9 days from month to month, consider methods like cervical mucus tracking or basal body temperature charting alongside the calendar for better insight.