CIDRworkbench
IPv4 + IPv6

NETWORK TOOLKIT / 01

Subnet Calculator.

Exact address ranges, masks, and network boundaries.

01

Define your network

Or use an IPv4 address and mask: 192.168.10.1 255.255.255.0

TRY
NETWORK OVERVIEWPrivate Network

192.168.10.0/24

Total Addresses256
Usable Addresses254
Prefix Length/24

Usable addresses exclude network and broadcast. Any gateway you assign uses one of these addresses.

FIRST USABLE192.168.10.1
LAST USABLE192.168.10.254
Network Address192.168.10.0
Last Address192.168.10.255
Subnet Mask255.255.255.0
Wildcard Mask0.0.0.255
Broadcast Address192.168.10.255
Address TypePrivate Network
02

Inside the address

32 bits · 4 octets
11000000
192
10101000
168
00001010
10
00000000
0
Network · 24 bitsHost · 8 bits
Reverse DNS & Delegation

PTR name for the input address

0.10.168.192.in-addr.arpa.

Network delegation

10.168.192.in-addr.arpa.
Standard Networking Rules

IPv4 LANs reserve network and broadcast addresses. /31 has 2 point-to-point addresses; /32 is a single host. IPv6 has no broadcast; total addresses are not an assignable-host guarantee.

Provider / Standard Reference ↗

Cloud profiles model subnet size and reservations, not full deployment eligibility. IPv6 total address space is not an assignable-host count.

Read an IPv4 Subnet at a Glance

Enter an address and prefix, such as 192.168.10.42/24, or an address and subnet mask. The calculator finds the containing network and shows its full range, usable range, wildcard mask and reverse DNS representation.

For 192.168.10.42/24, the network is 192.168.10.0/24, the mask is 255.255.255.0 and the broadcast is 192.168.10.255. The block contains 256 addresses. A standard LAN has 254 usable addresses, from 192.168.10.1 through 192.168.10.254. A gateway uses one of those addresses.

IPv6 Counts Without Rounding

An IPv6 /64 contains exactly 18,446,744,073,709,551,616 addresses. That is the size of the address space, not a promise of assignable host capacity. The calculator preserves exact counts and displays compressed and expanded notation. A /48 can be split into 65,536 /64 networks; split a smaller section at a time to stay within the 10,000-row limit.

Choose the Tool for the Job

  • Subnet Planner sizes LANs from host requirements, preserves existing allocations and allows for growth.
  • Range to CIDRs describes an exact set of addresses for firewall rules or inventories.
  • Cloud Subnets applies provider reservations before reporting usable IPv4 capacity.
  • CIDR Reference provides prefix tables and boundary explanations.

Export calculator results to CSV or Excel. Excel keeps long IPv6 values and large address counts as text.