What do the units mean?

DC++ has always measured file sizes and speeds with the understanding that 1024 of something make the next unit up.  One kibibyte is 1024; but when using the SI prefixes, one kilobyte is supposed to be 1000 bytes.  In DC++ v0.402, the units were changed to the more appropriate kilobinary prefixes decided upon by the International Electrotechnical Commission (IEC).
New Prefix
Factor
Old Prefix
Factor
kibi-
210 kilo-
103
mebi-
220 mega-
106
gibi-
230 giga-
109
tebi-
240 tera-
1012
pebi-
250 peta-
1015

For more information about the binary units see the National Institute of Standards and Technology .