Subnet Calculator — type an IP with CIDR (e.g. 192.168.1.50/24) to see the
network, broadcast, and host range instantly.
IP Info — enter a bare IPv4 address to see its class, type (private/public/loopback), binary,
hex, and reverse DNS form.
CIDR ↔ Mask — type a prefix like 24 or a dotted mask like
255.255.255.0 to convert between them.
Range Expander — enter a CIDR block to list every IP address in it (supported up to /23 = 512
addresses).
IPv6 — enter any shortened or full IPv6 address to expand it to its canonical 128-bit form,
compress it, and identify its type.
Frequently Asked Questions
What is CIDR notation?
CIDR
(Classless Inter-Domain Routing) pairs an IP address with a prefix length, e.g. 192.168.1.0/24. The number after
the slash counts the leading 1-bits in the subnet mask — /24 means 255.255.255.0.
How do I find the network address?
Bitwise-AND the IP with the subnet mask. For 192.168.1.50 AND 255.255.255.0 the result is 192.168.1.0 — the
network address. The Subnet Calculator tab does this for you.
What are private IP address ranges?
RFC
1918 defines three private ranges: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These are not routed on the
public internet. Loopback (127.0.0.0/8) and link-local (169.254.0.0/16) are also reserved.
What is the difference between network and
broadcast addresses?
The
network address (first in the block, all host bits = 0) identifies the subnet. The broadcast address (last, all
host bits = 1) sends packets to every host in the subnet. Neither can be assigned to a device.
What is a wildcard mask?
A
wildcard mask is the bitwise inverse of the subnet mask. Where the subnet mask has 1s (network bits), the
wildcard has 0s — and vice versa. Cisco ACLs and OSPF configurations use wildcard masks to specify which bits
must match.
How does the IPv6 expander work?
IPv6
shortens addresses by omitting leading zeros and replacing consecutive zero groups with ::. The expander pads
each group to four hex digits and fills :: with the correct number of zeroed groups to restore the full 128-bit
address.
What does /32 mean?
/32
means the entire 32-bit address is the network prefix — there are no host bits. It represents a single host
route. Subnet mask 255.255.255.255, total addresses: 1.
Did you know?
The entire IPv4 address space contains only ~4.3 billion addresses. IPv6 has 2¹²⁸ ≈ 340 undecillion — enough
to give every atom on Earth's surface its own address.
CIDR replaced the old class-based system (Class A/B/C) in 1993, letting ISPs allocate address blocks of any
size and dramatically slowing IPv4 exhaustion.
The 127.0.0.0/8 loopback range reserves 16 million addresses just so packets never leave the machine — only
127.0.0.1 is commonly used.
169.254.0.0/16 (link-local) addresses are self-assigned by devices when DHCP fails. If you see one on your
machine, it usually means the DHCP server is unreachable.