IPRangeExplorer

/19 vs /23 — Subnet Comparison

A /19 subnet is 16× larger than a /23. Every additional bit in the prefix halves the address space — the 4-bit difference between these two means /19 has 24 = 16 times as many addresses.

/19
Full reference →
Total IPs 8,192
Usable Hosts 8,190
Subnet Mask 255.255.224.0
Wildcard Mask 0.0.31.255
/23

512 IPs — two /24s combined

Full reference →
Total IPs 512
Usable Hosts 510
Subnet Mask 255.255.254.0
Wildcard Mask 0.0.1.255

Typical Uses

  • →Two-floor office network
  • →Expanded department VLAN
  • →Route aggregation of two /24s

Key Differences

16×
more IPs in /19 than /23
16
/23 subnets fit inside one /19
4
bits of difference in prefix length

How 16 /23 Subnets Divide a /19

Example using 10.0.0.0/19 as the parent block.

# CIDR Network First Usable Last Usable Broadcast Hosts
1 10.0.0.0/23 10.0.0.0 10.0.0.1 10.0.1.254 10.0.1.255 510
2 10.0.2.0/23 10.0.2.0 10.0.2.1 10.0.3.254 10.0.3.255 510
3 10.0.4.0/23 10.0.4.0 10.0.4.1 10.0.5.254 10.0.5.255 510
4 10.0.6.0/23 10.0.6.0 10.0.6.1 10.0.7.254 10.0.7.255 510
5 10.0.8.0/23 10.0.8.0 10.0.8.1 10.0.9.254 10.0.9.255 510
6 10.0.10.0/23 10.0.10.0 10.0.10.1 10.0.11.254 10.0.11.255 510
7 10.0.12.0/23 10.0.12.0 10.0.12.1 10.0.13.254 10.0.13.255 510
8 10.0.14.0/23 10.0.14.0 10.0.14.1 10.0.15.254 10.0.15.255 510
9 10.0.16.0/23 10.0.16.0 10.0.16.1 10.0.17.254 10.0.17.255 510
10 10.0.18.0/23 10.0.18.0 10.0.18.1 10.0.19.254 10.0.19.255 510
11 10.0.20.0/23 10.0.20.0 10.0.20.1 10.0.21.254 10.0.21.255 510
12 10.0.22.0/23 10.0.22.0 10.0.22.1 10.0.23.254 10.0.23.255 510
13 10.0.24.0/23 10.0.24.0 10.0.24.1 10.0.25.254 10.0.25.255 510
14 10.0.26.0/23 10.0.26.0 10.0.26.1 10.0.27.254 10.0.27.255 510
15 10.0.28.0/23 10.0.28.0 10.0.28.1 10.0.29.254 10.0.29.255 510
16 10.0.30.0/23 10.0.30.0 10.0.30.1 10.0.31.254 10.0.31.255 510

FAQ

What is the difference between /19 and /23?

A /19 has 8,190 usable hosts and a /23 has 510. The subnet masks differ: /19 uses 255.255.224.0 while /23 uses 255.255.254.0. Every additional bit in the prefix halves the number of addresses — so the 4-bit gap means /19 is exactly 16× larger.

How many /23 subnets fit in a /19?

Exactly 16 /23 subnets fit perfectly inside one /19 with no wasted space. To split a /19 into /23s, just increment the last 4 bits of the network address for each new subnet.

Which should I choose?

Choose based on how many hosts you need. Use the hosts → prefix calculator on the homepage to find the right size for your requirements.

Related Comparisons

/23 vs /24