SubnetPad

/23 Subnet Calculator

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A /23 block contains 512 addresses with 510 usable. Used for larger office floors, mid-size application tiers in cloud environments, and as a "super-net" spanning two /24 networks.

/1
/32

/23 = mask 255.255.254.0 • 510 usable addresses

Results for 192.168.0.0/23

Private (RFC 1918)Class C
Network addressThe first address — identifies the subnet itself
Broadcast addressThe last address — used to reach every device at once
Subnet maskSame as /23 in CIDR notation
First usable hostThe first IP you can assign to a device
Last usable hostThe last IP you can assign to a device
Usable hosts512 total addresses in this subnet
More detailsNeighboring subnets, wildcard mask, hex, reverse DNS, and binary breakdown

Neighboring /23 subnets

Wildcard mask
Used in Cisco ACLs and OSPF
CIDR notation
IP in hexadecimal
IP as 32-bit integer
Reverse DNS (PTR)
Host bits / subnet bits

Binary breakdown

IP address11000000.10101000.00000000.00000000
Subnet mask11111111.11111111.11111110.00000000
Network11000000.10101000.00000000.00000000
Broadcast11000000.10101000.00000001.11111111

Quick facts for /23

/23 reference guideBit split, overview, sizing tables, notable networks, and FAQ

Binary bit split

Network bits (23)Host bits (9)
Network bits
23
Host bits
9
Subnet mask
255.255.254.0
Wildcard mask
0.0.1.255
Total addresses
512
Usable hosts
510
Hosts formula
2^9 − 2
/24 relationship
2 × /24 networks

Overview

A /23 block contains 512 addresses with 510 usable. Used for larger office floors, mid-size application tiers in cloud environments, and as a "super-net" spanning two /24 networks.

Common use cases

  • Office floor or department network
  • Cloud application tier subnets
  • Hotel or conference Wi-Fi network
  • Span two /24 blocks into one summary route

Subnet sizing reference

Divide /23 into…

PrefixSubnetsHosts each
/242254
/254126
/26862
/271630

/23 fits inside…

SupernetHosts/23s inside
/221,0222
/212,0464
/204,0948
/198,19016

Notable /23 networks

  • 192.168.0.0/23Covers 192.168.0.x and 192.168.1.x

Frequently asked questions

Common questions about /23 networks, subnet masks, and use cases.

All CIDR prefix sizes

/0/1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16/17/18/19/20/21/22/23/24/25/26/27/28/29/30/31/32