IP Range Calculator for IPv4 Subnets
Quickly calculate the IPv4 address range that contains a given IP. The visualizer shows how the CIDR prefix determines block size, boundaries and usable host capacity.
How IPv4 subnet ranges work
Every CIDR prefix aligns an IPv4 address to a fixed-size block. The prefix length determines the block size, while the input IP determines which aligned block contains it.
A /28 contains 16 total addresses, a /27 contains 32, a /26 contains 64, and a /24 contains 256.
Example IP range calculation
For 10.20.30.44/28, /28 blocks advance in increments of 16 in the final octet. The address 44 belongs to the 32–47 block, so the network is 10.20.30.32 and the broadcast address is 10.20.30.47.
Full range vs usable host range
The full range includes every address in the CIDR block. In traditional IPv4 LAN subnetting, the first address represents the network and the last represents broadcast, so the usable host range excludes those two addresses. /31 and /32 are special cases.
When an IP range calculator is useful
Network engineers use ranges to validate firewall rules, DHCP pools, VPN scopes, cloud network allocations and route summaries. Developers and security teams also use them to determine whether a particular IP belongs inside a network block.
What this calculator shows
The result panel reports the canonical network address, broadcast address, first and last conventional usable addresses, dotted-decimal subnet mask, wildcard mask, total IPv4 address count and usable-host count. The live 32-bit boundary updates with the CIDR prefix, so the relationship between prefix length, block size and address capacity is visible instead of hidden behind a static table.
How to read the result correctly
The calculator normalizes the IP address you enter to the network block that contains it. That means an input such as 192.168.1.42/24 correctly resolves to network 192.168.1.0/24. For prefixes /0 through /30, conventional IPv4 subnetting reserves the first address as the network identifier and the final address as broadcast. /31 and /32 have different practical semantics, so their address counts should not be interpreted with the ordinary “subtract two” rule.
Related subnet tools
You can also use the subnetting cheat sheet for a complete IPv4 prefix reference, browse individual CIDR prefix pages, try the IPv6 subnet calculator, or return to the main visual subnet calculator.
Frequently asked questions
What is an IP range calculator?
It determines the aligned network block containing an IPv4 address and reports the network, broadcast, usable host range and block size.
What is the usable range of a /30?
A conventional /30 has four total addresses and two usable host addresses.
How do I know if two IPs are in the same subnet?
Apply the same subnet mask to both addresses. If the resulting network addresses are identical, the addresses are in the same subnet.