Image size compared to Bootcamp Partition Size

I have not purchased yet and have a question.
I have a Bootcamp Partition of 100GB.
The actual data on the partition is less than 50gbs.
How large can I expect the Winclone image to be? Will it reflect the size of the partition or the data contained in the partition?
I am concern about the space I will need to provide for the backup.

The image is about the size of the used data, which is then compress. It usually saves 5-40% with compression. We also do not copy mem files or the hibernate file, which can be large. Given your example of 50GB of used space, I would expect an image of 25-35GB.