How to manage azure blob size programmatically

Question

<pre lang="text">http://www.techxperiments.com/2015/10/14/block-blob-vs-page-blob-vs-append-blob/

https://docs.microsoft.com/en-us/rest/api/storageservices/fileservices/understanding-block-blobs--append-blobs--and-page-blobs

,After reading these article,I want to ask one question,that blob of all type are all fix size,files that we upload via app are vary in sizes too. problem is that if we fix the size of blob ,and if file size may be large or small then this block?this will be in both cases not suitable,e.g if block size large and file size small ,then this extra space is waste of money?and if file size greater than blob size then it will be loss of data?what will be the best solution?