Example
Input (CIDR)
192.168.1.0/24
Output
Network: 192.168.1.0 Broadcast: 192.168.1.255 Host range: 192.168.1.1 — 192.168.1.254 Usable hosts: 254 Netmask: 255.255.255.0 Wildcard: 0.0.0.255
Note
/24 = 32 - 24 = 8 bits of host = 2⁸ = 256 addresses (254 usable). /16 = 65,534 usable; /22 = 1022 usable. Private ranges: 10/8, 172.16/12, 192.168/16.
Usage / FAQ
When to use
- Compute CIDR ranges for firewall / security group rules
- Design VPC subnets on AWS, GCP, or Azure
- Check whether a specific IP falls inside a CIDR block
- Estimate usable IP counts for VPN and router setups
- Understand what `/24`, `/16`, `/22` really mean
FAQ
- Q.Why does /24 have only 254 hosts?
- A./24 covers 256 addresses (2⁸). The first (.0) is the network identifier, the last (.255) is the broadcast — only 254 are usable hosts. /31 and /32 are special (point-to-point / single host).
- Q.Is IPv6 supported?
- A.This tool covers IPv4 + CIDR only. IPv6 needs a dedicated tool. /64 is the de-facto subnet size for IPv6 — one LAN holds ~2^64 addresses.
- Q.What are private ranges?
- A.Per RFC 1918: 10.0.0.0/8 (Class A), 172.16.0.0/12 (Class B), 192.168.0.0/16 (Class C). Not routed on the public internet, free to use inside homes and offices.
Fun facts
CIDR (Classless Inter-Domain Routing) was introduced in 1993 via RFC 1519. The old Class A/B/C system (fixed blocks of 16M / 65K / 256 hosts) was burning through IPv4 too fast, so the switch was to arbitrary-bit-length prefixes — that's where '/24', '/27' notation comes from.
RFC 1519 (1993)IANA's last free IPv4 /8 block was allocated to the regional registries on February 3, 2011 — the free pool was officially exhausted. Since then, IPv4 addresses have effectively been a tradable asset, with market prices of tens of dollars per address.
Wikipedia — IPv4 exhaustionThe private IP ranges (RFC 1918 — 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) were standardized in 1996. Combined with NAT, they're the single biggest trick that delayed IPv4 exhaustion by 25+ years — every home router's LAN range comes from here.
RFC 1918 (1996)
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