CIDR and subnet calculator

IP to CIDR - simple

Input lower and upper IP (either IPv4 or IPv6) of the range - the tool will calculate best matching CIDR range. Subnet will be included in result.



IP to CIDR - advanced

Input at least two IP's (IPv4 and/or IPv6), domainnames or CIDR ranges to include - the tool will calculate best matching CIDR ranges. Subnet will be included in result. Seperate by space, tab, newline or comma.


IPv4 max network prefix:

IPv6 max network prefix:

Reverse - CIDR to IP + subnet

Input one or more CIDR ranges to get info of IP addresses and subnet.


CIDR to IP result

37.218.216.0/21


CIDR
37.218.216.0/21

This CIDR range reference a lot of IP's - be cautious about using this, in a security context.

lower IP
37.218.216.0


upper IP
37.218.223.255


subnet
255.255.248.0


broadcast
37.218.223.255


count
2.048



byte no: 1 2 3 4
bit no:

 1-8

 9-16

 17-24

 25-32
value: 37 218 216 0
bit pattern:
0
0
1
0
0
1
0
1
1
1
0
1
1
0
1
0
1
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
prefix:
/21
 

Log

  • Parseing '37.218.216.0/21' into 2.048 IP's