Online IP Subnet Mask Calculator

 


 

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Click here for an example calculation

/0  0.0.0.0         /1  128.0.0.0       /2  192.0.0.0       /3  224.0.0.0
/4  240.0.0.0       /5  248.0.0.0       /6  252.0.0.0       /7  254.0.0.0

/8  255.0.0.0       /9  255.128.0.0     /10 255.192.0.0     /11 255.224.0.0
/12 255.240.0.0     /13 255.248.0.0     /14 255.252.0.0     /15 255.254.0.0

/16 255.255.0.0     /17 255.255.128.0   /18 255.255.192.0   /19 255.255.224.0
/20 255.255.240.0   /21 255.255.248.0   /22 255.255.252.0   /23 255.255.254.0

/24 255.255.255.0   /25 255.255.255.128 /26 255.255.255.192 /27 255.255.255.224
/28 255.255.255.240 /29 255.255.255.248 /30 255.255.255.252 /31 255.255.255.254

/32 255.255.255.255


My method of working out subnets that is > /24

If we take the address 192.168.4.18/29

/29 is just the number of bits used for the subnet mask. So the subnet mask will
be 255.255.255.248.

if we use 256-248 = 8, with this mask 0-255 is broken up into groups of 8.


Network Address (18 taken from address above)

integer(18/8) = 2
              * 8
              = 16
192.168.4.16


Broadcast Address (18 taken from address above)

integer(18/8) = 2
              + 1
              = 3
              * 8
              = 24
              - 1
              = 23
192.168.4.23