You can not calculate the median, you can only find/identify it:

Sort the data and take the value in the middle of the sorted list. This is the median.

If the list has an even number of values, there is no unique "middle value". In this case the median is not well defined and there are several competeing ways proposed how to estimate the median in such cases. The simplest and I think most often used solution is to use the average of the two middle values as the median.

Thanks Jochen, but i asked how to do it in grads tool?

The middle value will be the middle value, no matter in what unit these values are.

Thanks alot Jochen sir.