Use cases and examples

This page walks through common real-world scenarios to show how IP Calculator’s features work together.

1. Planning a small office network

You have been assigned 192.168.1.0/24 and need to allocate subnets for four groups with different sizes:

• Servers — 10 hosts
• Workstations — 50 hosts
• Guest Wi-Fi — 30 hosts
• Printers — 5 hosts

Steps:

1. Switch to the VLSM tab.
2. Enter 192.168.1.0 as the address and 24 as the prefix.
3. Add four requirements: “Workstations” with 50 hosts, “Guest Wi-Fi” with 30 hosts, “Servers” with 10 hosts, and “Printers” with 5 hosts.
4. The Allocations table will show the optimal subnet for each requirement. For example, Workstations might receive 192.168.1.0/26 (62 usable hosts) and Printers might receive 192.168.1.192/29 (6 usable hosts).
5. Check the Free Space section to see how much room remains for future growth.
6. Click Export to save the allocation plan as CSV or HTML.

2. Splitting a /16 into department subnets

Your organisation owns 10.10.0.0/16 and you need to carve it into subnets for different departments, not all the same size.

Steps:

1. In the Calculator tab, enter 10.10.0.0 with prefix 16.
2. Use the Split into / control to set the child prefix to /24. This shows all 256 possible /24 subnets.
3. On the Subnet Map, right-click a subnet and select Split to divide it further — for example, split a /24 into two /25 subnets for a smaller department.
4. Use Join with next or Join with previous to merge adjacent subnets into a larger block for a department that needs more addresses.
5. Continue splitting and joining until the layout matches your requirements. Use Ctrl+Z to undo any mistakes.

3. Summarising routes for a routing table

You have several contiguous /24 networks and want to advertise them as a single summary route.

Steps:

1. Switch to the Supernet tab.
2. Enter the networks, one per line:
   10.0.0.0/24
10.0.1.0/24
10.0.2.0/24
10.0.3.0/24
3. The Summary Routes table shows the result: 10.0.0.0/22 covering all 1024 addresses.
4. The message “Routes successfully summarised” confirms an exact summary with no wasted space.

If your networks are not contiguous (e.g. 10.0.0.0/24 and 10.0.5.0/24), the result will contain multiple summary routes, and the message “Cannot be reduced to a single route” will appear.

4. Auditing IP allocations for conflicts

Different teams have submitted their subnet assignments and you need to check for overlaps before deploying them.

Steps:

1. Switch to the Overlap tab.
2. Enter all subnets, one per line, or click Load File… to import them from a text file:
   10.1.0.0/16
10.1.5.0/24
10.1.5.0/24
10.2.0.0/16
3. Review the Relationships table. You will see:
   • 10.1.0.0/16 CONTAINS 10.1.5.0/24 — one team’s broad allocation includes another team’s specific subnet.
   • 10.1.5.0/24 is IDENTICAL to 10.1.5.0/24 — a duplicate entry that needs to be resolved.
   • 10.1.0.0/16 and 10.2.0.0/16 show no overlap.
4. Use the Network Visualisation chart to see the relative sizes and positions of all networks at a glance.

5. Understanding a /27 subnet for CCNA study

You need to work out the details of 172.16.5.64/27 for an exam question.

Steps:

1. In the Calculator tab, enter 172.16.5.64 with prefix 27.
2. Read the Network Details:
   • Network: 172.16.5.64
   • Broadcast: 172.16.5.95
   • First Host: 172.16.5.65
   • Last Host: 172.16.5.94
   • Usable Hosts: 30
3. Read the Mask Details:
   • Subnet Mask: 255.255.255.224
   • Wildcard: 0.0.0.31
   • Mask Bits: 27, Host Bits: 5
4. Look at the Binary Visualisation to see 27 network bits (coloured) followed by 5 host bits. This confirms that the last 5 bits determine host addresses within the subnet, giving 2⁵ = 32 total addresses (30 usable after removing the network and broadcast addresses).