ITS LIKE THIS:

b = bit
B = Byte
Kib = kibibit
kb = kilobit
KiB = kibibyte
kB = kilobyte
Mb = megabit
MiB = mebibyte
MB = megabyte
Gb = gigabit
GiB = gibibyte
GB = gigabyte
Tb = terabit
TiB = tebibyte
TB= terabyte
Pb = petabit
PiB = pebibyte
PB = petabyte
Eb = exabit
EiB = exbibyte
EB = exabyte

so here is it with speeds

bs = bit/s
Bs = Byte/s
Kibs = kibibit/s
kbs = kilobit/s
KiBs = kibibyte/s
kBs = kilobyte/s
Mbs = megabit/s
MiBs = mebibyte/s
MBs = megabyte/s
Gbs = gigabit/s
GiBs = gibibyte/s
GBs = gigabyte/s
Tbs = terabit/s
TiBs = tebibyte/s
TBs = terabyte/s
Pbs = petabit/s
PiBs = pebibyte/s
PBs = petabyte/s
Ebs = exabit/s
EiBs = exbibyte/s
EBs = exabyte/s

Usually ips write what speed you get in kbs(kilobits/s).

For example: If your badwidth is 256 kbps then here kb means kilobits which means your

Download speed = 256/8 = 32kB/sec.

And now i will try to explain how you can convert kbs to KBs etc:

1000 bit = 1 kilobit
1000 kilobit = 1 megabit
1000 megabit = 1 gigabit
1000 gigabit = 1 terabit
1000 terabit = 1 petabit
1000 petabit = 1 exabit

1024 bits = 1 kibibit
1024 byte = 1 kibibyte
1024 kibibyte = 1 mebibyte
1024 mebibyte = 1 gibibyte
1024 gibibyte = 1 tebibyte
1024 tebibyte = 1 pebibyte
1024 pebibyte = 1 exbibyte

8 bit = 1 byte
1024 byte = 1 kilobyte
1024 kilobyte = 1 megabyte
1024 megabyte = 1 gigabyte
1024 gigabyte = 1 terabyte
1024 terabyte = 1 petabyte
1024 petabyte = 1 exabyte

Well this doesnt help us much, cuz we need to figure out how many 1 megabit is in kilobyte

1 kilobit = 1000 bit = 125 byte
1 megabit = 1000 kilobit = 125 kilobyte
1 gigabit = 1000 megabit = 125000 kilobyte
1 terabit = 1000 gigabit = 125000000 kilobyte
1 petabit = 1000 terabit = 125000000000 kilobyte

I hope this explains a bit, and if not, im just gonna try to give a few examples. on some known connection types, that ppl usually have with fiber or adsl.

256kilobit/s(256kbs) = 32kilobyte/s or 32kB/s or
512kilobit/s(512kbs) = 64kilobyte or 64kB/s or
768kilobit/s(768kbs) = 96kilobyte or 96kB/s or
1mbit/s(1mbs/1mbits) = 125kilobyte or 125kB/s or
10mbit/s(10mbs/10mbits) = 1250kilobyte or 1250kB/s or

and just for those who doesnt know, "/s" means "per second" so 256kbs = 256 kilobit per sec