The unique glass basal thermometer

The Geratherm® basal offers you a sustainable alternative to hormonal contraception. The fertile days and ovulation can be identified through a daily morning measurement of the body temperature and a correct documentation. It is important to measure the body temperature immediately after waking up and definitely before getting up. In contrast to the Geratherm® classic, the basal thermometer has a more precise scale, which is accurate to two decimal places.


Important documents


The basal thermometer is made exclusively (95%) with raw materials from Germany and can be completely recycled.

Suitable for allergy sufferers

This thermoter is ideal for allergy sufferers. The closed glass body is free of metals or plastics. It can also be cleaned and disinfected 100% safely.

Without batteries

The measuring principle of the thermometer is based on the thermal expansion of materials, which is why this thermometer does not need batteries. The non-toxic measuring liquid Galinstan replaces the previously known mercury.

Special glass from Germany

We only use special glass from Germany to manufacture our thermometer. The glass tube and the internal capillary are manufactured in-house.

Technical Data

Measuring range 35,60 °C to 38,40 °C
Measurement accuracy +0,1 °C / - 0,1 °C
Intended purpose Analog basal thermometer for cycle control
Measuring locations vaginal, rectal, oral, axillary
Storage conditions -15 °C to 39 °C

You have to reset the measuring liquid of the thermometer before each measurement, in our case it means shaking the thermometer.

Hold the thermometer between your thumb and forefinger. The tip of the thermometer points towards the ground. Make sure that no objects such as a table, chair, etc. in your immediate environment that could break the thermometer. Now start shaking your wrist with quick movements. The measuring liquid sinks.

Note: Contrary to the hard hitting of the thermometer known in the past, you now need speed. Today's Galinstan has different material properties than the mercury of the past.

To make it easier for you to lower the measuring liquid, we have developed a shaking aid called "easy flip" for the Geratherm classic. Push the thermometer into this and hold it at the upper end. Then start shaking it. The plastic begins to vibrate and amplifies the natural movement, resulting in faster fluid reset.

This is the only way to reduce the measuring liquid. Fridge, cold water & co are useless.


The silver line you see at 38°C is a calibration mark. This indicates that there is a temperature of 38 °C at this exact position of the measuring liquid. This marking is required for the production process and ensures the measuring accuracy of the thermometer.

You can reuse the Geratherm® basal glass thermometer as often as you like. Clean your thermometer before each use.

Important! If the thermometer is cracked or already broken, stop using it. Dispose of this in the household waste.

The Geratherm® basal should be cleaned after and before each measurement. Since it is a closed glass body, you can wash it with soap and water and then dry it. The water must never be hotter than 42 °C. You can also easily disinfect the thermometer. Immersion disinfection is also possible.  

At the top of the chart are the days of your cycle from 1 to 42, you can add more if conducive. Above each day of the cycle write its date. The vertical temperatures are 35 °C applied up to 38 °C. Draw your temperature with a dot. Mark the days when you had sexual intercourse.

1 to 2 days after ovulation (ovulation), the basal body temperature rises by 0.2 to 0.5 °C and remains at this high level until beginning of the next cycle. (Right before the day of ovulation, a drop of about 0.1°C can often be observed.) In the event that ovulation has occurred if the temperature rise should have occurred within 48 hours. When you are about 3 Once you have filled out the tables, you will receive an ovulation chart and you will recognize your individual fertility chart.

Ovulation or ovulation means that the ovary releases an egg, this is the prerequisite for the fertilization of the egg cell by a sperm in the fallopian tube. Certain changes can occur in the body, e.g. B. the appearance of a thin, clear vaginal mucus that appears just before ovulation, i. H. approximately between the 10th and 12th day of your monthly cycle exits the cervix. This mucus has the job of keeping the sperm alive until ovulation.
Another symptom can be a slight pain in the left or right side at the time of actual ovulation be. With a regular monthly cycle of 28 days, approximately the days between the 10th and 14th day are the days when you are most likely to get pregnant. But every woman has her individual cycle and the fewest ovulate regularly in the middle of the cycle.