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IP Subnet Calculator Examples
The IP Subnet Calculator performs complete subnet calculations for network planning, IP address management, and cloud infrastructure design. Below are examples covering basic subnetting, subnet division, VLSM, and IPv6.
Basic Subnet Calculation
Input: 192.168.1.0/24
Network Address: 192.168.1.0
Subnet Mask: 255.255.255.0
Wildcard Mask: 0.0.0.255
Broadcast Address: 192.168.1.255
First Usable Host: 192.168.1.1
Last Usable Host: 192.168.1.254
Total Hosts: 256
Usable Hosts: 254
Binary Mask: 11111111.11111111.11111111.00000000
IP Class: C
Address Type: Private
Subnet Calculation with Dotted Decimal Mask
Input: 10.0.0.0 / 255.255.0.0
CIDR Notation: 10.0.0.0/16
Network Address: 10.0.0.0
Subnet Mask: 255.255.0.0
Wildcard Mask: 0.0.255.255
Broadcast Address: 10.0.255.255
First Usable Host: 10.0.0.1
Last Usable Host: 10.0.255.254
Total Hosts: 65,536
Usable Hosts: 65,534
Dividing a Network into Subnets
Divide 192.168.1.0/24 into 4 equal subnets:
Input: 192.168.1.0/24, divide into 4 subnets
New prefix length: /26 (borrows 2 bits: 2^2 = 4 subnets)
Each subnet has 64 addresses (62 usable hosts)
Subnet 1: 192.168.1.0/26
Network: 192.168.1.0
Broadcast: 192.168.1.63
Host Range: 192.168.1.1 – 192.168.1.62
Subnet 2: 192.168.1.64/26
Network: 192.168.1.64
Broadcast: 192.168.1.127
Host Range: 192.168.1.65 – 192.168.1.126
Subnet 3: 192.168.1.128/26
Network: 192.168.1.128
Broadcast: 192.168.1.191
Host Range: 192.168.1.129 – 192.168.1.190
Subnet 4: 192.168.1.192/26
Network: 192.168.1.192
Broadcast: 192.168.1.255
Host Range: 192.168.1.193 – 192.168.1.254
VLSM (Variable Length Subnet Masking)
VLSM allocates different subnet sizes based on actual requirements, minimizing wasted addresses.
Available network: 10.1.0.0/16
Requirements:
- Department A: 500 hosts
- Department B: 200 hosts
- Department C: 50 hosts
- Point-to-Point Link: 2 hosts
VLSM Allocation (largest first):
Department A — needs 500 hosts → /23 (510 usable)
Subnet: 10.1.0.0/23
Range: 10.1.0.1 – 10.1.1.254
Department B — needs 200 hosts → /24 (254 usable)
Subnet: 10.1.2.0/24
Range: 10.1.2.1 – 10.1.2.254
Department C — needs 50 hosts → /26 (62 usable)
Subnet: 10.1.3.0/26
Range: 10.1.3.1 – 10.1.3.62
P2P Link — needs 2 hosts → /30 (2 usable)
Subnet: 10.1.3.64/30
Range: 10.1.3.65 – 10.1.3.66
Remaining: 10.1.3.68/30 and beyond (available for future use)
Supernetting (Route Summarization)
Summarize these four networks into one route:
192.168.0.0/24
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
Binary analysis:
192.168.0.0 = 11000000.10101000.00000000.00000000
192.168.1.0 = 11000000.10101000.00000001.00000000
192.168.2.0 = 11000000.10101000.00000010.00000000
192.168.3.0 = 11000000.10101000.00000011.00000000
Common bits: 22
Summary route: 192.168.0.0/22
Covers: 192.168.0.0 – 192.168.3.255
Total addresses: 1,024
Cloud Network Planning (AWS VPC Example)
VPC CIDR: 10.0.0.0/16 (65,536 addresses)
Subnet design for 3 availability zones:
Public Subnets (for load balancers):
us-east-1a: 10.0.0.0/24 (254 hosts)
us-east-1b: 10.0.1.0/24 (254 hosts)
us-east-1c: 10.0.2.0/24 (254 hosts)
Private App Subnets (for EC2 instances):
us-east-1a: 10.0.10.0/23 (510 hosts)
us-east-1b: 10.0.12.0/23 (510 hosts)
us-east-1c: 10.0.14.0/23 (510 hosts)
Private DB Subnets (for RDS):
us-east-1a: 10.0.20.0/24 (254 hosts)
us-east-1b: 10.0.21.0/24 (254 hosts)
us-east-1c: 10.0.22.0/24 (254 hosts)
Remaining: 10.0.23.0 – 10.0.255.255 (reserved for future growth)
IPv6 Subnet Calculation
Input: 2001:db8::/32
Prefix Length: /32
Network: 2001:db8::
Total Addresses: 2^96 = 79,228,162,514,264,337,593,543,950,336
Divide into /48 subnets (typical per-site allocation):
Each /48 provides 2^80 addresses
Number of /48 subnets in /32: 2^16 = 65,536
Example /48 subnets:
2001:db8:0000::/48 (Site 1)
2001:db8:0001::/48 (Site 2)
2001:db8:0002::/48 (Site 3)
Each /48 can be divided into /64 subnets:
Number of /64 subnets per /48: 2^16 = 65,536
Each /64 has 2^64 host addresses
Wildcard Mask Reference
Wildcard masks are the inverse of subnet masks, used in ACLs and OSPF configurations.
Subnet Mask CIDR Wildcard Mask Hosts
255.255.255.252 /30 0.0.0.3 2
255.255.255.248 /29 0.0.0.7 6
255.255.255.240 /28 0.0.0.15 14
255.255.255.224 /27 0.0.0.31 30
255.255.255.192 /26 0.0.0.63 62
255.255.255.128 /25 0.0.0.127 126
255.255.255.0 /24 0.0.0.255 254
255.255.254.0 /23 0.0.1.255 510
255.255.252.0 /22 0.0.3.255 1,022
255.255.0.0 /16 0.0.255.255 65,534
255.0.0.0 /8 0.255.255.255 16,777,214
Enter any IP address with a prefix length or subnet mask to get complete subnet details, or use the subnet division feature to plan your network layout from scratch.