When a new cycle starts, the NC° algorithm initially predicts your next period based on your average cycle length.
However, your period prediction will update once ovulation has been detected in your current cycle. In order to predict your cycle length more accurately, the algorithm will consider your ovulation date and your average luteal phase length.
Since your luteal phase usually remains rather stable from cycle to cycle (although the length varies from person to person), your average luteal phase length can help predict your next period more accurately once ovulation is detected.
Why is the algorithm predicting my period on a different day than my usual cycle length?
If the algorithm is predicting a longer cycle than usual, this could be because it detected ovulation later than usual in your cycle, and adding your average luteal phase length to that late ovulation will delay your period prediction. Similarly, if your current cycle is predicted to be shorter, this could be because your ovulation was detected earlier than usual.
Should you get your period on a different day than what the prediction indicates, simply log it as you usually would, and the algorithm will adjust accordingly.
Note: If you don’t log any temperature data, the algorithm won’t be able to detect ovulation, and that means that it won’t be able to accurately predict your next period. As described above, the detected ovulation plays an important role in the prediction of your next period. For that reason, we encourage you to log temperature as often as you can so the algorithm can accurately analyze your cycle and give you personalized and accurate predictions.