Difficulties cloning a HDD to SSD of the same size

[Apex_Impulse]

I am trying to clone an HDD with Windows 7 installed on it on to a Samsung 850 EVO using the Samsung Data Migration software. Both drives are of the same nominal size (500 GB), and the same actual size (roughly 465 GB).The HDD in question is not entirely full, it's got around 428 GB on it as it sits.
The migration tool is telling me that I need to delete 56 GB off the HDD to clone it. That seems WAY too high, even with overprovisioning taken into account. Could anyone tell me why I need to reduce the amount being cloned so much? And how can I get around it, if it's at all possible?

 

[USAFRet]

The Samsung software won't do it if it believes the target drive is too small.
For instance, with a 250GB target SSD, it will not do it if the source data is over 200GB. Scaling up, what it is telling you is typical and correct.

Remove some stuff.