The title is quite self-explanatory, but here is the more detailed info:
I do MHDD scans regularly, and I detected *potential* bad sectors in my hard drive. Note the word "potential": it's not red, it's not green, no way near unc "x" but definitely problematic — as regular grey dots patterns were detected.

So this is what I want: I want to partition out a range of sectors starting from, say LBA 500,000,000 to LBA 900,000,000.

The problem I'm having is, I don't know how to do that. I recall all the partition tools are based on MB or KB instead of LBA.

So do I use some kind of MB to LBA equation to do that or is there actually a tool that allow me to use LBA as basis?

For those who ask why don't I just remap it: I can't, they are not really bad sectors, not even showing up as green dots, but definitely problematic. I'm nipping the problem in its bud.

The grey dot pattern you describe is normal, so I wouldn't bother trying to map them out.

But if you really want to anyway, there are many partition tools that can help. Or you can do the math to use the partition tool you are used to. What size is your hard drive and is the partition table MBR or GPT or something else? If running Windows and the drive is 2 TB or less then you probably have a MBR partition table. If MBR, then most Linux distros have the "fdisk" command which allows partition size values based on blocks (Windows cluster) or cylinders as well as MB. Or you can edit the disk directly. On a MBR disk the partition table will be on sector 0 at offset 446. There are 4 16-byte entries starting at offset 446 in the format of: status (1-byte), CHS address of 1st sector (3-bytes), partition type (1-byte), CHS address of last sector (3-bytes), LBA of 1st sector (4-bytes), number of sectors in partition (4-bytes). So if your sectors 500M - 900M are in the middle of the disk then you could make 3 partitions:
Partition 1: LBA 2,048 - 499,999,999
Partition 2: LBA 500,000,000 - 900,000,000
Partition 3: LBA 900,000,001 - end of disk

Another thing to keep in mind is that if your disk is one of the newer "advanced partition" disks with a 4k sector size then you may want to make sure your partitions are aligned on the 4k boundary or you could see performance issues with some operating systems or programs.

Or use your favorite tool and make 3 partitions:
Partition 1: 256 GB (or 238.42 GiB / 252,723 MiB)
Partition 2: 195.8 GB (or 190.73 GiB / 186,730 MiB) (this should be about LBA 500,000,000 - 900,000,000)
Partition 3: rest of the disk

Again, I wouldn't bother because what you describe is normal, but if you are really bored or just want to learn about partition tables then go for it.

Thank you for your reply, the grey pattern is normal? I've never thought that way and most new disks don't appear to have that kind of pattern. the pattern goes like this:
H= normal light grey sectors ,#= potentially problematic dark grey sectors:
HH#HHHH
HHH#HHH
#HHH#HH
H#HHH#H

Dunno about you but I think it's pretty scary. Those grey dots are all located at the end of a 320G disk, LBA 950,000,000 till the end of the entire disk.

The reading and writing speed are lower when it comes to that area, and I may have files corrupted (odd though, since there is no unc "x" "red dot" sectors, so it's unlikely) there. I'm still trying to confirm that.

2048 512-byte sectors = 1 megabyte
1024 megabytes = 1 gigabyte

you can translate LBAs to GBs with these

however, I'd leave it as it is. Drive will normally get slower towards higher LBAs, with darker blocks towards the end.