Ovulation Calculator

Find out what day to start using Ovry Ovulation Test Strips to detect your most fertile time of the month. Scroll down to start.

What day did your last period start?

Not sure when your period started?


The first day of your last period is considered Day 1 of your cycle.

* Please select date

What is your average cycle length?

Cycle length is measured from the first day of bleeding (Day 1) to the day before your next period begins. The average cycle length is 28 days, but often varies between 21 and 40 days. If your cycle length is irregular, that is, if it varies by more than a few days each month, use the average number of days for the last 3 months. If your cycle is regularly less than 21 days long or greater than 40 days long, please consult a physician to determine when you should begin testing for ovulation.

* Please average cycle length

What is your email address ?

* Please include your average cycle length

You should begin testing with Ovry® Ovulation Test Strips on:

If you aren't sure when your last period started and/or how long your cycle is, we recommend:

1) Waiting for your next period to start and noting that day in a calendar and

2) Counting the number of days from the date you marked down until the date that your following period begins (you can use that calculated number as your cycle length).

If you haven't done this, you don't know the answers to the questions above and you'd still like to use our tests, we recommend starting on day 10 of your cycle. However, without knowing your average cycle length there is more risk in missing the LH surge due to testing too late.