svan71 :
each model is $200 more than i'm comfortable spending, at least they should be 512 and 1024. The storage numbers bs should be dealt with. I purchased a 4tb drive once formatted it's 3.6. Thats 400 gb lost simply making the drive usable.
You don't lose 400 GB due to "formatting" - that's a marketing lie that generally hasn't been applicable since floppy disks. On floppies you could change the amount of space the disk could hold by altering the number/layout of the magnetic tracks - but people don't do that kind of thing with HDDs. SSDs are not magnetic so it is literally impossible to change the amount of flash memory available by changing the format. You can't change physical chips using software. Format in this case means the physical arrangement of data, not what filesystem is being used on the disk.
Now, formatting a disk in Windows generally means to initialize a specific file system (FAT, NTFS) on the disk.
When you format (add a file system) a drive with windows, you do lose a few hundred megabytes as the drive needs a space to save where the files are located. But Windows will display this as used space, not by reducing overall capacity.
To windows, 1 GB = 2^30 Bytes = 1073741824 Bytes
To storage marketers 1 GB is redefined to 10^9 = " 1 Billion Bytes" (There was a lawsuit to stop this because for most other industries it is illegal to redefine units of measure, but the storage companies won since "giga" can mean 10^9 in scientific notation)
What actually ends up on the (raw/"unformatted") drive is often a little bit less than the advertised "1 Billion Bytes", and I have not yet found any other explanation other than false advertisement. I don't think this is a case of over provisioning, but it's not like there's many people out there testing various drives for their true capacites.
Since the old definition of 1GB = 2^30 Bytes is very important for a lot of technical reasons, computer scientists invented a new word "Gibbibyte" to use instead. So now the abbreviation is 1GiB = 2^30 Bytes. Windows still uses the old abbreviation of GB (and maybe Mac/Linux?, I've seen it both ways in android) when they really mean GiB. There is a whole set of equivalents to expresses capacities in binary:
1 Tebibyte (TiB)= 1024 GiB
1024 Mebibyte (MiB) = 1 GiB etc.
Basically say the old words as if you were a baby, and you have the new words. Yes, it's very dumb sounding but extremely important for engineers to be able to speak about this stuff in a non-ambiguous way.
Anyways, the reason you have less capacity than you think you should, is because 1 GB is about 7% smaller than 1 GiB. But the gap gets worse as you move between orders of magnitude. So 1 TB is more like 9% smaller than 1 TiB.
Check an online calculator and you'll see
4TB = 3.63798 TiB (which you'll see as 3.6 TB in Windows) = 3725 GiB
TL;DR Hard drive storage capacities are a deliberately confusing mess, and marketers get away with their obsolete "formatting" explanation because most people don't know the difference. All the data you "lose" never existed in the first place and some judge said that's legal, because of technicalities and math. Also, OS makers aren't exactly helping the situation. 
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