IP Subnet Masks

So IP subnet masks can be a bit tricky. Some IP’s are usable, some are not, and /24  is a different number than how many IP’s are available or even used. What I mean is for 100 IP’s why not go /100 seams easy enough lol. Well Computer programmers are infamous for making things harder than they need to be. I guess  to scare off the easily timid. Luckily I found this really simple chart listing the translation for all the common Subnet masks.

Net bitsSubnet masktotal-addresses per subnet
/20255.255.240.04096
/21255.255.248.02048
/22255.255.252.01024
/23255.255.254.0512
/24255.255.255.0256
/25255.255.255.128128
/26255.255.255.19264
/27255.255.255.22432
/28255.255.255.24016
/29255.255.255.2488
/30255.255.255.2524