Smart Period Calculator

Wouldn’t it be great to look into the future and see when your next period is coming up?

We made a period calculator that learns about you and your cycles. We use a sophisticated machine learning algorithm to predict your period over the course of the next few months.

How to use the period calculator

So, what is this all about?

Let me make a bold statement: All period calculators out there are complete garbage. Why? Because they usually ask you for your average cycle length and do a very basic calculation by adding the average length over and over again.

Have you noticed that your natural cycle isn’t always exactly 28 days long? It’s a myth that the female cycle is always 28 days long.

From a medical perspective, if your cycles’ length is between 23 and 35 days, your cycles are considered regular.

There was a study in which gynecologists analyzed 9,846 cycles of healthy women between 19 and 45. They found out that only 13% of these women have a typical 28 day cycle. About 50% of the women had cycles that were longer than 28 days and every tenth cycle was shorter than 25 days.

See the following diagram which shows the distribution of 9846 cycle lengths:

Chart showing frequency of cycle lengths

You might say that a regular cycle has about 27 days, give or take a day or two. But that wouldn’t be correct either. The following diagram shows that the cycle lengths can fluctuate quite a bit:

Chart showing cycle length fluctuations

There’s one remarkable take-away: 58% of these women have cycle lengths that vary 7 days or more.

This means that it’s pretty normal if you experience a cycle that is only 25 days long, followed by another cycle that is 31 days long.

What does that mean for calculating my period?

Say you want to calculate your period 3 months into the future. Your cycle lengths change merely by 2-3 days. In the worst case, a normal period calculator would be off by 6-9 days, which is a lot.

Whenever a period calculator tells you an exact result, it is lying to you.

We made a better period calculator, which predicts your next periods based on your individual previous cycles and your individual period duration. These individual factors are combined with a general statistical model we derived from over 80,000 female cycles.

In other words: Our period calculator gets to know you. It learns more about you and your cycle as you enter more data.

I see a lot of red days in the future

You’ll see that our period calculator is simply honest. Your next menstrual cycle cannot be predicted accurately. Our period calculator takes that into account. If you check 6 months into the future, you’ll notice that the prediction is pretty inaccurate, because it’s true. This is the only prediction anyone can ever make about your cycles (if you don’t suppress your cycle with hormones like the pill).

Ok got it, what do I do now with the period calculator?

The advantage of our period calculator is that there are still a few days marked white. It is highly unlikely that you’ll get your period on one of these days in the future. This allows you to plan ahead, if you have a bit of flexibility in your schedules:

Questions? Write us!

admin /AT/ period-calculator /DOT/ com


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