Cycle and Fertility – How to Calculate Ovulation

Your menstrual cycle tells you more than you might think. It is a window into your fertility – and by knowing your patterns, you can better plan and understand your body’s signals.

What is a menstrual cycle?

A cycle is counted from the first day of your period until the day before your next period begins. An average cycle lasts 28 days, but anything between 24 and 35 days can be normal.

When do you ovulate?

Ovulation typically occurs 12–16 days before your next period. In a 28-day cycle, this is often around day 14. But the timing can vary – which is why it’s important to observe signs and, if needed, use calculation methods.

Signs of ovulation

• Changes in cervical mucus – clear and stretchy like raw egg white
• Slight increase in body temperature after ovulation (measured with a basal thermometer)
• Mild pain on one side of the lower abdomen
• Increased libido and breast tenderness

How to calculate your cycle and ovulation

1. Note the first day of your period for several months.
2. Find the average number of days between your periods.
3. Subtract 14 days from the first day of your next period – this gives an estimated time for ovulation.

If your cycle is irregular, it may help to use apps, LH tests, or basal temperature tracking to find patterns.

When are you most fertile?

The fertile window lasts about 5 days leading up to and including ovulation day. Sperm can survive up to 5 days, while the egg can only be fertilized for about 12–24 hours after ovulation. Knowing your fertile window is therefore the key to timing.

Frequently Asked Questions

How do I know if my cycle is normal?

A regular cycle between 24 and 35 days, with less than 8 days of variation from month to month, is considered normal.

Can stress affect my ovulation?

Yes. Stress can disrupt hormone production and thereby delay or even prevent ovulation.

Is there a difference between ovulation and fertility?

Ovulation is a sign of fertility, but overall fertility also depends on egg quality, the uterine lining, and other factors.

Should I use LH tests?

They can be helpful in identifying the LH surge before ovulation – especially if your cycle is irregular.

When should I seek help?

If you’ve been trying to get pregnant for over 12 months (or 6 months if you’re over 35), it is recommended to contact a fertility clinic.

Do you want to learn more about your cycle and get support in understanding your fertility patterns? At La Roar Life Science, we offer personal consultations where we look at your lifestyle, cycle, and options together. Our FertilityCare® with zinc, which contributes to normal fertility and reproduction, and folate, which contributes to maternal tissue growth during pregnancy, can be part of your journey. Book a free 1:1 consultation and receive personal guidance today.