Enter any IPv4 CIDR block and get the network address, broadcast, usable host range, subnet mask, wildcard, and binary breakdown. Works offline in your browser — no data leaves the page.
a.b.c.d/n where n is 0–32. Examples: 192.168.1.0/24, 10.0.0.0/8, 172.16.5.0/22.| Network address | — |
| Broadcast address | — |
| First usable host | — |
| Last usable host | — |
| Subnet mask | — |
| Wildcard mask | — |
| Prefix length | — |
| Host bits | — |
| IP class (historical) | — |
| Private / public | — |
CIDR (Classless Inter-Domain Routing) notation describes an IP network with one short string: an IP address, a slash, and a prefix length. The prefix tells you how many of the leading bits belong to the network — the rest are available for individual hosts.
For an IPv4 block a.b.c.d/n:
/31 has two usable hosts (point-to-point links), and /32 has one (single host)./32 — 1 address (single host, firewall rules)/30 — 4 addresses, 2 usable (point-to-point legacy)/29 — 8 addresses, 6 usable (small device blocks)/28 — 16 addresses, 14 usable (small subnets; AWS reserves 5, leaving 11)/27 — 32 addresses, 30 usable/24 — 256 addresses, 254 usable (a typical LAN segment, common AZ subnet)/22 — 1,024 addresses (small office)/20 — 4,096 addresses (mid-size segment)/16 — 65,536 addresses (typical VPC top-level CIDR)/12 — 1,048,576 addresses (172.16.0.0/12 private range)/8 — 16,777,216 addresses (10.0.0.0/8 private range)These ranges are reserved for private networks and are not routable on the public internet:
10.0.0.0/8172.16.0.0/12192.168.0.0/16If you're designing a VPC or home lab, pick a block from one of these ranges. Most cloud VPCs default to something inside 10.0.0.0/8.
192.168.1.0/24 — the IP address followed by a slash and the prefix length. The prefix length is the number of bits used for the network portion. /24 means the first 24 bits identify the network, leaving 8 bits for hosts (256 addresses, 254 usable)./n, total addresses = 2^(32-n). Usable hosts = total minus 2 (subtracting the network address and the broadcast address), except for /31 (point-to-point, 2 usable) and /32 (single host, 1 usable). For example, /24 has 256 total and 254 usable hosts; /16 has 65,536 total and 65,534 usable./24 is equivalent to the subnet mask 255.255.255.0. CIDR is more compact and is the standard in modern networking and cloud configuration. Subnet masks are still used in many legacy interfaces and on-prem network gear./24 (mask 255.255.255.0), the wildcard mask is 0.0.0.255. Wildcard masks are used by Cisco ACLs and OSPF configurations to define which IP address bits should be matched and which should be ignored./16 is the most common top-level VPC CIDR (65,536 addresses), with /24 subnets per availability zone (256 addresses each). For smaller environments, a /20 VPC with /27 subnets is also common. AWS allows VPC CIDRs from /16 to /28; subnets from /16 to /28. Each subnet reserves 5 addresses for AWS use, so a /28 subnet has 11 usable hosts in AWS, not 14./32 specifies a single IP address — all 32 bits are network. It's commonly used in firewall rules, route tables, and load balancer target groups to refer to one specific host. For example, 203.0.113.5/32 means exactly that one address.JobsByCulture tracks backend, SRE, platform, and DevOps roles at the companies engineers actually want to work at — from frontier AI labs to cloud-native scale-ups.
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