IPRangeExplorer

/11 vs /15 — Subnet Comparison

A /11 subnet is 16× larger than a /15. Every additional bit in the prefix halves the address space — the 4-bit difference between these two means /11 has 24 = 16 times as many addresses.

/11
Full reference →
Total IPs 2,097,152
Usable Hosts 2,097,150
Subnet Mask 255.224.0.0
Wildcard Mask 0.31.255.255
/15
Full reference →
Total IPs 131,072
Usable Hosts 131,070
Subnet Mask 255.254.0.0
Wildcard Mask 0.1.255.255

Key Differences

16×
more IPs in /11 than /15
16
/15 subnets fit inside one /11
4
bits of difference in prefix length

How 16 /15 Subnets Divide a /11

Example using 10.0.0.0/11 as the parent block.

# CIDR Network First Usable Last Usable Broadcast Hosts
1 10.0.0.0/15 10.0.0.0 10.0.0.1 10.1.255.254 10.1.255.255 131,070
2 10.2.0.0/15 10.2.0.0 10.2.0.1 10.3.255.254 10.3.255.255 131,070
3 10.4.0.0/15 10.4.0.0 10.4.0.1 10.5.255.254 10.5.255.255 131,070
4 10.6.0.0/15 10.6.0.0 10.6.0.1 10.7.255.254 10.7.255.255 131,070
5 10.8.0.0/15 10.8.0.0 10.8.0.1 10.9.255.254 10.9.255.255 131,070
6 10.10.0.0/15 10.10.0.0 10.10.0.1 10.11.255.254 10.11.255.255 131,070
7 10.12.0.0/15 10.12.0.0 10.12.0.1 10.13.255.254 10.13.255.255 131,070
8 10.14.0.0/15 10.14.0.0 10.14.0.1 10.15.255.254 10.15.255.255 131,070
9 10.16.0.0/15 10.16.0.0 10.16.0.1 10.17.255.254 10.17.255.255 131,070
10 10.18.0.0/15 10.18.0.0 10.18.0.1 10.19.255.254 10.19.255.255 131,070
11 10.20.0.0/15 10.20.0.0 10.20.0.1 10.21.255.254 10.21.255.255 131,070
12 10.22.0.0/15 10.22.0.0 10.22.0.1 10.23.255.254 10.23.255.255 131,070
13 10.24.0.0/15 10.24.0.0 10.24.0.1 10.25.255.254 10.25.255.255 131,070
14 10.26.0.0/15 10.26.0.0 10.26.0.1 10.27.255.254 10.27.255.255 131,070
15 10.28.0.0/15 10.28.0.0 10.28.0.1 10.29.255.254 10.29.255.255 131,070
16 10.30.0.0/15 10.30.0.0 10.30.0.1 10.31.255.254 10.31.255.255 131,070

FAQ

What is the difference between /11 and /15?

A /11 has 2,097,150 usable hosts and a /15 has 131,070. The subnet masks differ: /11 uses 255.224.0.0 while /15 uses 255.254.0.0. Every additional bit in the prefix halves the number of addresses — so the 4-bit gap means /11 is exactly 16× larger.

How many /15 subnets fit in a /11?

Exactly 16 /15 subnets fit perfectly inside one /11 with no wasted space. To split a /11 into /15s, 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.