Subnet Calculator (CIDR)
IPv4 network, broadcast, host range and mask from CIDR.
About this tool
Enter an IPv4 address with a prefix like 10.0.0.0/24, or with a netmask, to get the network and broadcast addresses, usable host range, host count, wildcard mask and binary view. You can also check whether another address belongs to the subnet.
How to use it
- Enter an IPv4 address with a prefix, like 192.168.1.10/24, or with a netmask.
- Read the network, broadcast, host range, netmask, wildcard and number of usable hosts.
- Check whether another address is inside the subnet.
- Optionally split the network into smaller subnets with a longer prefix.
Questions
- What does /24 mean?
- It is the prefix length: the first 24 bits are the network part and the remaining 8 bits number the hosts. A /24 has 256 addresses, of which 254 can be assigned to hosts.
- Why are two addresses not usable?
- The first address identifies the network and the last is the broadcast address. Point-to-point /31 links (RFC 3021) and single-host /32 routes are the exceptions.
- 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 used for carrier-grade NAT. These addresses are not routed on the public internet.
- What is a wildcard mask?
- The inverse of the netmask, used in Cisco ACLs and OSPF. For 255.255.255.0 the wildcard is 0.0.0.255.
Something not working, or a result looks wrong? Report a problem with this tool