You must measure your temperature using a basal thermometer with two decimals. You cannot use a regular fever thermometer together with Natural Cycles.
For those of you that just started, it's good to know that it will take a few weeks of measuring for Natural Cycles' algorithm to learn your unique cycle. You can exclude the temperature due to 'slept differently' on the weekends if you enjoy sleeping in during those days.
You should measure first thing when you wake up in the morning before you sit up or get out of bed.
The basal body temperature is our temperature at rest, and it is lowest when we sleep. Moving too much will affect your body temperature, and the result will be incorrect. We recommend that you measure at least five times per week. We advise all Cyclers to measure at roughly the same time every morning you choose to measure on after the same amount of sleep, within a ± 2h window of your usual morning alarm. If you decide to sleep in, then we recommend that you still measure to keep up the habit, but that you exclude the temperature for that day.
Place the thermometer under your tongue and close your mouth before you press ON.
Place the thermometer in your mouth and under your tongue, as far back as possible, next to the root of your tongue. You can start measuring once the thermometer is in the correct position in your mouth. Wait for the beeps, which indicate that the thermometer is done measuring your temperature.
For the first three 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 ovulate. The better Natural Cycles knows your cycles, the more precise the algorithm will be in detecting your ovulation, and in return, you will get a narrower window of red days.
Click here for more information on when to exclude your temperature. When you mark your temperature as excluding, the algorithm doesn't take it into account in the calculations.