IPRangeExplorer

/15 vs /19 — Subnet Comparison

A /15 subnet is 16× larger than a /19. Every additional bit in the prefix halves the address space — the 4-bit difference between these two means /15 has 24 = 16 times as many addresses.

/15
Full reference →
Total IPs 131,072
Usable Hosts 131,070
Subnet Mask 255.254.0.0
Wildcard Mask 0.1.255.255
/19
Full reference →
Total IPs 8,192
Usable Hosts 8,190
Subnet Mask 255.255.224.0
Wildcard Mask 0.0.31.255

Key Differences

16×
more IPs in /15 than /19
16
/19 subnets fit inside one /15
4
bits of difference in prefix length

How 16 /19 Subnets Divide a /15

Example using 10.0.0.0/15 as the parent block.

# CIDR Network First Usable Last Usable Broadcast Hosts
1 10.0.0.0/19 10.0.0.0 10.0.0.1 10.0.31.254 10.0.31.255 8,190
2 10.0.32.0/19 10.0.32.0 10.0.32.1 10.0.63.254 10.0.63.255 8,190
3 10.0.64.0/19 10.0.64.0 10.0.64.1 10.0.95.254 10.0.95.255 8,190
4 10.0.96.0/19 10.0.96.0 10.0.96.1 10.0.127.254 10.0.127.255 8,190
5 10.0.128.0/19 10.0.128.0 10.0.128.1 10.0.159.254 10.0.159.255 8,190
6 10.0.160.0/19 10.0.160.0 10.0.160.1 10.0.191.254 10.0.191.255 8,190
7 10.0.192.0/19 10.0.192.0 10.0.192.1 10.0.223.254 10.0.223.255 8,190
8 10.0.224.0/19 10.0.224.0 10.0.224.1 10.0.255.254 10.0.255.255 8,190
9 10.1.0.0/19 10.1.0.0 10.1.0.1 10.1.31.254 10.1.31.255 8,190
10 10.1.32.0/19 10.1.32.0 10.1.32.1 10.1.63.254 10.1.63.255 8,190
11 10.1.64.0/19 10.1.64.0 10.1.64.1 10.1.95.254 10.1.95.255 8,190
12 10.1.96.0/19 10.1.96.0 10.1.96.1 10.1.127.254 10.1.127.255 8,190
13 10.1.128.0/19 10.1.128.0 10.1.128.1 10.1.159.254 10.1.159.255 8,190
14 10.1.160.0/19 10.1.160.0 10.1.160.1 10.1.191.254 10.1.191.255 8,190
15 10.1.192.0/19 10.1.192.0 10.1.192.1 10.1.223.254 10.1.223.255 8,190
16 10.1.224.0/19 10.1.224.0 10.1.224.1 10.1.255.254 10.1.255.255 8,190

FAQ

What is the difference between /15 and /19?

A /15 has 131,070 usable hosts and a /19 has 8,190. The subnet masks differ: /15 uses 255.254.0.0 while /19 uses 255.255.224.0. Every additional bit in the prefix halves the number of addresses — so the 4-bit gap means /15 is exactly 16× larger.

How many /19 subnets fit in a /15?

Exactly 16 /19 subnets fit perfectly inside one /15 with no wasted space. To split a /15 into /19s, 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.