IP / CIDR
Inspect IPv4 CIDR ranges — network, broadcast, mask, and host count.
- CIDR
- Address
- Netmask
- Wildcard
- Network
- Broadcast
- First host
- Last host
- Total addr
- 256
- Usable hosts
- 254
- Class
- C
- Scope
- Private (RFC 1918)
Binary
- Address
- 11000000.10101000.00000001.00001010
- Mask
- 11111111.11111111.11111111.00000000
- Network
- 11000000.10101000.00000001.00000000
Contains
Notes
- IPv4 only for now.
- Usable host count subtracts network + broadcast for /30 and shorter. /31 follows RFC 3021 (2 hosts), /32 is a single host.
- Click any value to copy it.
- Pure JavaScript bitmath — your input never leaves the browser.
CIDR, addresses, and ranges
CIDR (Classless Inter-Domain Routing) notation writes a block of IP addresses as address/prefix-length. The prefix length tells you how many of the 32 bits identify the network; the remaining bits identify hosts inside it. Paste any IPv4 CIDR — or a bare address, which is treated as /32 — and this tool computes the network, broadcast, usable host range, subnet mask, and total address count.
Reading a prefix length
/24— 256 addresses, 254 usable hosts. The classic "home network" size./16— 65,536 addresses. Common for medium corporate networks./30— 4 addresses, 2 usable. Used for point-to-point links between routers./32— a single host. The form used to whitelist one machine in a firewall rule./0— the entire IPv4 address space. The default route.
Network, broadcast, and usable hosts
Inside any subnet larger than /31, the first address is reserved as the network identifier and the last address is reserved as the broadcast address. The remaining addresses are usable for hosts. /31 and /32 are special cases:/31 is used for point-to-point links where both addresses can be assigned to hosts, and /32 represents a single address with no network or broadcast at all.
Containment checks
A common operational question is "does this address fall inside that subnet?" Pasting an address followed by a subnet (or vice versa) and reading off the range answers this in a glance — useful for triaging firewall logs, checking VPN routing tables, and spotting overlapping ranges before a network change.