Resize-VHD -SizeBytes $Value

Hi

This part of code in script it doesn't work:

$Size=Read-Host "Define new disk size"
Resize-VHD -Path x:\VHD\Disk.vhdx -SizeBytes $Size

How to use this value $size?
User cannot put 1TB or 10GB or even 123123123 as bytes becuse script generate error.

Erorr:
Resize-VHD : Cannot bind parameter 'SizeBytes'. Cannot convert value "0.2TB" to type "System.UInt64". Error: "Input string was not in a correct format."

Kind Regards Tomasz