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IP Subnet (CIDR) Calculator

Calculate network and broadcast addresses, usable host range, subnet mask and wildcard for any IPv4 CIDR block. Check whether an IP is in a subnet, split networks and convert IP ranges to CIDR.

Runs locally — your input never leaves this page.

Network
Broadcast
First host
Last host
Usable hosts
Total addresses
Subnet mask
Wildcard mask
Class
Type

Binary

 
 
   
 
 
 
 Split into  
 
 
     
     
     
     
     
     
    IP range → CIDR
     
       
     
     
     
     
    Prefix cheat sheet
     
      
     /32 255.255.255.255 1 
     /31 255.255.255.254 2 
     /30 255.255.255.252 2 
     /29 255.255.255.248 6 
     /28 255.255.255.240 14 
     /27 255.255.255.224 30 
     /26 255.255.255.192 62 
     /25 255.255.255.128 126 
     /24 255.255.255.0 254 
     /23 255.255.254.0 510 
     /22 255.255.252.0 1,022 
     /21 255.255.248.0 2,046 
     /20 255.255.240.0 4,094 
     /16 255.255.0.0 65,534 
     /12 255.240.0.0 1,048,574 
     /8 255.0.0.0 16,777,214 
          
     
     
     
      
     
     
     
    How to use
     
       
    1. Enter an address with a prefix (192.168.1.10/24) or a mask (10.0.0.1 255.255.0.0). You can also pick the prefix from the menu.
    2. Read the network, broadcast, first and last usable host, mask and wildcard — each can be copied.
    3. Type another IP in “Is this IP in the subnet?” to check membership, or split the block into smaller subnets.
    4. Use “IP range → CIDR” to get the minimal list of CIDR blocks covering a start–end range, e.g. for firewall rules.
      5.  
      
    FAQ
     
     
      Why are there 2 fewer usable hosts than addresses?  
    In a normal subnet the first address identifies the network and the last is the broadcast address, so neither can be assigned to a host. /31 (point-to-point links, RFC 3021) and /32 (a single host) are exceptions.
     
      What is a wildcard mask?  
    The inverse of the subnet mask (for /24, 0.0.0.255). Cisco ACLs and OSPF configuration use it to describe which bits may vary.
     
      Which ranges are private?  
    10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 (RFC 1918). 100.64.0.0/10 is carrier-grade NAT, 127.0.0.0/8 is loopback and 169.254.0.0/16 is link-local — the calculator labels each of these.
     
     
     
      Report a bug or suggest a feature →