Enter a CIDR block above or click a sample to calculate the IP range
What is CIDR
Free CIDR to IP range calculator — convert any CIDR block
CIDR (Classless Inter-Domain Routing) notation represents an IP address block as a base IP and a prefix length separated by a slash — for example, 192.168.1.0/24. The prefix number (24) tells you how many bits identify the network, with the remaining bits available for host addresses. A /24 has 8 host bits, giving 256 total IPs and 254 usable hosts.
This free CIDR to IP range calculator converts any CIDR block into its full IP range instantly — showing the network address, broadcast address, first and last usable host, subnet mask, wildcard mask, and total host count. It also identifies whether the range is a private RFC 1918 address, loopback, link-local, multicast, or public IP block.
All calculations happen in your browser — no data is sent to any server. Supports all IPv4 prefixes from /0 (the entire internet) to /32 (a single host).
What this tool does
Network Address
The first IP in the range — identifies the subnet itself. Cannot be assigned to a host device.
Broadcast Address
The last IP in the range — used to address all hosts in the subnet simultaneously. Cannot be assigned to a host.
First Usable Host
The first IP that can be assigned to a device — always network address + 1 (except /31, /32).
Last Usable Host
The last assignable IP — always broadcast address - 1 (except /31, /32).
Subnet Mask
The bitmask that separates network bits from host bits. Used in routing tables and interface configuration.
Wildcard Mask
The inverse of the subnet mask. Used in Cisco ACLs and OSPF route configuration.
Usable Hosts
Total IPs minus 2 (network + broadcast). This is how many devices the subnet can support.
Address Type
Whether the block is private (RFC 1918), public, loopback, link-local, or multicast.
Examples
CIDR to IP range — real-world examples
Click any sample in the tool above to calculate it instantly. These examples cover the most common CIDR blocks used in networking.
Most common
192.168.1.0/24 — Small office LAN — 254 usable hosts
The /24 is the most common subnet in home and small office networks. It provides 254 usable IPs — enough for most private LANs. The 192.168.x.x range is reserved for private use (RFC 1918) and is not routable on the public internet.
Network
192.168.1.0
Broadcast
192.168.1.255
First host
192.168.1.1
Last host
192.168.1.254
Usable hosts
254
Large private network
10.0.0.0/8 — Class A private range — 16 million hosts
The 10.0.0.0/8 block is the largest RFC 1918 private range, providing over 16 million usable IPs. Used by large enterprises, cloud VPCs, and data centers that need vast internal addressing space.
Network
10.0.0.0
Broadcast
10.255.255.255
First host
10.0.0.1
Last host
10.255.255.254
Usable hosts
16,777,214
Point-to-point link
10.10.10.0/30 — /30 point-to-point link — 2 usable hosts
A /30 provides exactly 2 usable IPs, making it ideal for point-to-point links between routers. One IP is assigned to each end of the link. Commonly used on WAN interfaces and inter-router connections.
Network
10.10.10.0
Broadcast
10.10.10.3
First host
10.10.10.1
Last host
10.10.10.2
Usable hosts
2
Small segment
10.10.10.0/28 — /28 segment — 14 usable hosts
A /28 provides 14 usable IPs — used for small server segments, DMZ networks, or subnetting a larger range into small zones. Subnet mask is 255.255.255.240.
Network
10.10.10.0
Broadcast
10.10.10.15
First host
10.10.10.1
Last host
10.10.10.14
Usable hosts
14
Subnet quick reference
| CIDR | Subnet Mask | Total IPs | Usable Hosts | Common Use |
|---|---|---|---|---|
| /8 | 255.0.0.0 | 16,777,216 | 16,777,214 | Large enterprise / RFC 1918 Class A |
| /16 | 255.255.0.0 | 65,536 | 65,534 | Medium network / RFC 1918 Class B |
| /24 | 255.255.255.0 | 256 | 254 | Small office LAN (most common) |
| /25 | 255.255.255.128 | 128 | 126 | Half of a /24 |
| /26 | 255.255.255.192 | 64 | 62 | Quarter of a /24 |
| /27 | 255.255.255.224 | 32 | 30 | Small segment |
| /28 | 255.255.255.240 | 16 | 14 | Very small segment / DMZ |
| /29 | 255.255.255.248 | 8 | 6 | Point-to-point with extras |
| /30 | 255.255.255.252 | 4 | 2 | Point-to-point link |
| /31 | 255.255.255.254 | 2 | 2 | Point-to-point (RFC 3021) |
| /32 | 255.255.255.255 | 1 | 1 | Single host / host route |
FAQ
Frequently asked questions
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation represents an IP address and its network prefix length. For example, 192.168.1.0/24 means the IP address 192.168.1.0 with a 24-bit network prefix, leaving 8 bits for host addresses — 256 total IPs and 254 usable hosts. CIDR replaced the older Class A/B/C system and allows flexible allocation of IP address blocks. Enter any CIDR block above to instantly see the network address, broadcast address, and full host range. Enter any CIDR block above to instantly see the network address, broadcast address, and full IP range.
How do I convert CIDR to an IP range?
Enter your CIDR block into the calculator above (e.g. 10.0.0.0/24) and the tool instantly shows the full IP range: network address (first IP), broadcast address (last IP), first usable host, last usable host, and total IP count. The network address is the CIDR base IP with the host bits zeroed. The broadcast address has all host bits set to 1.
How are usable hosts calculated from a CIDR block?
Usable hosts = 2^(32 - prefix) - 2. The subtraction of 2 accounts for the network address (first IP, used to identify the subnet) and the broadcast address (last IP, used to address all hosts simultaneously). For a /24: 2^8 - 2 = 254 usable hosts. For /31 and /32, all addresses are usable per RFC 3021. The formula is 2^(32-prefix) minus 2 -- except /31 gives 2 usable hosts and /32 gives exactly 1. The formula is 2^(32-prefix) minus 2 for network and broadcast — except /31 gives 2 usable hosts and /32 gives 1.
What is the difference between network address and broadcast address?
The network address is the first IP in a CIDR block and identifies the subnet itself — it cannot be assigned to a device. The broadcast address is the last IP and is used to send packets to all hosts in the subnet simultaneously — it also cannot be assigned to a device. All assignable host IPs fall between these two addresses.
What is a wildcard mask and how is it different from a subnet mask?
A wildcard mask is the bitwise inverse of the subnet mask. Where a subnet mask uses 1s to identify the network portion, a wildcard mask uses 0s to mean match and 1s to mean ignore. For a /24 (subnet mask 255.255.255.0), the wildcard is 0.0.0.255. Wildcard masks are used in Cisco ACLs, OSPF routing, and firewall rules. For example, a wildcard of 0.0.0.255 matches any host in a /24 block, while 0.0.0.0 matches only the exact IP specified. For example, a wildcard of 0.0.0.255 matches any host in a /24 block, while 0.0.0.0 matches only the exact IP.
What are the private IP address ranges?
RFC 1918 defines three private IPv4 ranges not routable on the public internet: 10.0.0.0/8 (16,777,214 usable hosts), 172.16.0.0/12 (1,048,574 usable hosts), and 192.168.0.0/16 (65,534 usable hosts). These are used inside private networks and translated to public IPs by NAT routers. This calculator automatically identifies private ranges. Private IPs are non-routable on the public internet and are reserved exclusively for internal network use. Private IPs are non-routable on the public internet and are used for internal networks in homes, offices, and data centres.
What does /32 mean in CIDR notation?
A /32 prefix means all 32 bits identify the network, leaving zero bits for hosts — it represents a single specific IP address. /32 is used for loopback addresses, host routes, and specifying individual IPs in firewall rules. The network address, broadcast address, and only usable host are all the same IP. A /32 is commonly used in host routes, loopback entries, and firewall rules targeting a single specific machine. A /32 is commonly used in host routes, loopback entries, and firewall rules targeting a single specific machine.
What is the difference between /24, /25, and /26?
A /24 has 256 IPs (254 usable), a /25 splits a /24 in half giving 128 IPs (126 usable) each, and a /26 splits into quarters giving 64 IPs (62 usable) each. Each reduction of 1 in the prefix halves the number of available IP addresses. Use the subnet reference table in this calculator to compare common prefix sizes. Halving the prefix length (for example /24 to /23) doubles the address space -- each additional bit doubles it again. Halving the prefix length (e.g. /24 to /23) doubles the address space; each additional bit doubles it again.
How do I find the IP range from a CIDR block?
Use the calculator above — enter the CIDR block and the first and last IP of the range are shown immediately. The first IP is always the network address, the last is the broadcast address. The usable host range runs from network+1 to broadcast-1 (except for /31 and /32). Enter the CIDR block above and the full host range is calculated and displayed instantly alongside the subnet mask. Enter the CIDR block in the tool above and the full IP range is displayed instantly alongside the subnet mask and host count.
Is this CIDR calculator free and does it require signup?
Yes — completely free with no signup, no account, and no usage limits. All CIDR calculations happen in your browser using pure JavaScript. Nothing is sent to any server. All subnet calculations use standard binary arithmetic locally -- no account, login, or API key required. All subnet calculations are performed locally using standard binary arithmetic — no account or API key required.
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