There are two scenarios where position data is transmitted to the server:
- During live tracking. In this scenario position data will be sent to the server with an interval as configured in the settings. This data only contains the positions captured since the last time the mobile phone contacted the server successfully. The amount of data sent depends on the number of positions captured. If you drive on a straight road, not so many positions will be captured. However, if you walk on a meandering path, there will be more. Just to give an indication: on average less than 1 kb of data is sent and received. This often involves just a few positions in every request.
- During transmission of a complete track afterwards (manually activated using the Send data menu). These tracks show up on the Saved tracks list on the website. In this request the number of positions can be several hundreds. For about 275 positions in a track about 30 kb of data will be sent.
Besides these scenarios, data will also be transmitted during requests for the position of your friends (only if you have enabled this). Again this depends on the time interval you configured and the number of friends in your friendslist.
However, by far the most data will be spent when using the map feature! For every map visible this can run into 120 kb. If you use the map feature and leave it running while moving, data usage will increase rapidly because new map information has to be downloaded over and over again. That's the reason for the warning when starting the map feature for the first time.
If you want to exactly track your data usage, it will help to install software that measures data traffic. This will help keep control of the costs.
The data traffic costs depend on the GSM service provider that you are using. Contact your service provider for more information.