Network tool
CIDR calculator
Enter an IPv4 or IPv6 CIDR network. Host-prefix input such as 8.8.8.8/24 is accepted and normalized to the canonical network.
- Input
- 2001:db8::1/128
- Canonical network
- 2001:db8::1/128
- IP version
- IPv6
- Prefix length
- 128
- Network address
- 2001:db8::1
- First address
- 2001:db8::1
- Last address
- 2001:db8::1
- Total addresses
- 1
- Netmask
- Not used for IPv6
- Broadcast
- Not used for IPv6
- Usable hosts
- N/A
What this tool does
The CIDR calculator normalizes a network, calculates its first and last address, counts total addresses, and shows IPv4-specific netmask, broadcast, and usable host values.
Use it when a firewall, DNS provider, hosting panel, or network document gives you CIDR notation and you need the actual address range. Start with the CIDR notation guide if the slash number is unfamiliar.