The basal body temperature (BBT) varies from person to person and also depends on where you measure it.
You can measure your basal body temperature orally, vaginally, or rectally.
Measuring the temperature vaginally or rectally will generally lead to higher temperatures than measuring orally. For that reason, you must always measure in the same way.
If you want to change your measuring method, you should always do so at the start of a new cycle. It can then take around 1-3 cycles for the algorithm to adjust to your new way of measuring, and during this time, you can expect more Red Days (for NC° Birth Control) or Brown Days (for NC° Plan Pregnancy).
Note: If you are struggling with your measuring routine, know that you now have the option to use Natural Cycles with one of our approved wearable devices (the Oura Ring and the Apple Watch). When using Natural Cycles with a wearable device, your temperature data gets measured overnight while you sleep. This means that you no longer need to remember to take your temperature before getting out of bed in the morning! Learn more about using Natural Cycles with the Oura Ring here, and with the Apple Watch here.
You can also refer to the Instructions for Use for any questions you have about using this thermometer.