Calculating fertile days with the calendar method?

Discover the advantages of Daysy and the practical ovulation app DaysyView!

Have you settled for natural family planning and want to use the calendar method for contraception? Then you should know that this method is very unsafe and strictly not recommended by experts, because your cycle can change at any time. A little bit of stress at work or a small flu is enough for your calculations to no longer be true without you even noticing it. It practically only makes sense to calculate your fertile days with the calendar method if you want to get pregnant and do not care about how quickly you conceive. In this case, you can estimate your fertile days with the help of a personal ovulation calendar and use them for unprotected sex. But for contraception, the calendar method is anything but suited!

crop for Daysy website.jpgovulation calendar

Daysy gives you more than 99% accuracy!

Daysy distinguishes your fertile from your infertile days for you with an accuracy of more than 99%!  Daysy makes your natural family planning easy and comfortable. 

In order for Daysy to be able to calculate your fertile days as precisely as possible, you have to use it every morning prior to getting up. All you need to do is measure the basal temperature underneath your tongue and wait until you hear a signal sound. The measurement takes a maximum of 60 seconds! Later Daysy might ask you to confirm via the push of a button that you are currently on your period. You will immediately see via a colorful light whether you are currently fertile or not.

Red means that you are fertile and should avoid to have sex on those days, or alternatively use an additional barrier method like a condom or a diaphragm when you are having sex. If Daysy's light is green it means that you will not be fertile within the next 24 hours and can forego contraception when you have sex. Daysy always shows you precisely when you have to use contraception.

Calculate your fertile days: have an overview with Daysy's ovulation calendar

But Daysy offers you even more: With the practical ovulation app DaysyView for your smartphone you can keep an eye on your current ovulation calendar or view a practical preview of the next month. The preview is also ideally suited to plan activities for when you do not want to be menstruating, such as going swimming or doing certain types of exercise. DaysyView also displays your temperature curve. Beyond that you can also take notes in Daysy's ovulation app and record, for instance, when you have had sex. If you want, you can also share this calendar with your partner. This way, he too will know in advance when to use contraception.

With Daysy and its app DaysyView nothing stands in between natural family planning and a self-determined love life!


Daysy is a fertility tracker that uses the fertility awareness method by learning and tracking your menstrual cycle.