When and how to measure

It is very important that you measure your temperature using a basal thermometer with 2 decimals. You are not to use a regular fever thermometer together with Natural Cycles.

Measure first thing in the morning,  before you get out of bed or lie awake.
The basal body temperature is our resting temperature, and it is lowest when we sleep. The slightest movement (sitting up, or getting out of the bed) will affect your body temperature and the result will be incorrect. We advise Natural Cycles users to measure at roughly the same time every morning after the same amount of sleep, within a ± 2h window of your usual morning alarm. If you decide to have a lie-in then we suggest skipping measuring that morning. It is OK to skip measuring on the days when you sleep more than 2 hours more/less than normal, for example on the weekends.
For those of you that just started, it's good to know that it will take a few weeks of measuring for Natural Cycles to understand your unique cycle. The more data, the better can we know where in your cycle you are, so keep measuring!
We recommend that you measure 5 times per week, so you can skip the weekends if you enjoy sleep-ins during those days. 

Place the thermometer under your tongue before you press ON.
Almost the entire purple part of the thermometer will be inside of the mouth when the thermometer is placed correctly. Close your mouth and breathe through your nose. Start measuring once the thermometer is correctly placed in your mouth. Wait for the beeps which indicate that the thermometer is done with measuring.

For the first 3 cycles, measure as often as possible to help the app get to know you.
The more data points you have, the better Natural Cycles can get to know you and know when you typically ovulate. The better Natural Cycles knows your cycles the more certain the algorithm is of when you ovulate, and in return, you will get a narrow window of possibly fertile days.
When NOT to measure:
  • When you’re sick, regardless of if you have a fever or not
  • ​If you have had alcohol the night before. 1-2 glasses of wine (or similar) for dinner is okay. If in doubt, always tap deviating temperature after you've entered the temperature
  • If you wake up more than 2 hours later/earlier than usual (long sleep-in or very early rise)
  • Once you’re out of bed, sitting up, or after laying awake for a while
  • If you have snoozed. Measure after the first alarm, then you can snooze all you want
Remember that your temperature is what the algorithm is using to be able to confirm ovulation in each cycle. So if you have a lot of red, fertile, days it may be a good idea to check your graph if you haven't already. Please read more about how the app detects ovulation

Here is a video on how and when to measure your basal body temperature: