Network Segmentation Calculator

Calculator Inputs

Base Network Address

Base Prefix

Number of Departments

Current Hosts per Segment

Growth Percentage

Redundancy Percentage

Security Tier

Reserved VLAN Count

Segment Name Prefix

Example Data Table

Department	Users	Devices per User	Estimated Hosts	Recommended Segment	Suggested VLAN
Finance	30	3	90	/25	101
Engineering	60	4	240	/24	102
HR	18	2	36	/26	103
Guest Wi-Fi	75	1	75	/25	104

Formula Used

1. Adjusted hosts per segment
Adjusted Hosts = Current Hosts × (1 + Growth %) × (1 + Redundancy %) × Security Multiplier

2. Recommended subnet size
Choose the smallest prefix where usable hosts are greater than or equal to adjusted hosts.

3. Available subnet count
Available Subnets = 2^{(Recommended Prefix − Base Prefix)}

4. Usable hosts in a subnet
For prefixes /30 and larger networks: Usable Hosts = 2^{(32 − Prefix)} − 2

5. Utilization
Utilization % = (Total Assigned Hosts ÷ Base Network Usable Hosts) × 100

How to Use This Calculator

Enter the base IPv4 network and its prefix length.
Provide the number of departments or logical security zones.
Enter the current host count needed inside each segment.
Add expected growth and redundancy percentages for spare capacity.
Select the security tier to reflect stronger isolation planning.
Set any extra VLAN reserve needed for future projects.
Click the calculate button to generate the segment plan.
Review the summary, allocation table, chart, and export options.

FAQs

1. What does this calculator estimate?

It estimates subnet sizing, VLAN count, host capacity, spare headroom, and segmentation feasibility inside a chosen base IPv4 network.

2. Why is growth percentage important?

Growth percentage adds forward-looking capacity so new devices, staff increases, and added services do not exhaust the subnet too quickly.

3. What does the security tier change?

The security tier increases planning overhead. Stronger isolation often needs more reserved address space, policy boundaries, and future micro-segmentation flexibility.

4. Does this support IPv6?

No. This version focuses on IPv4 subnet planning. You can extend the logic later for IPv6 prefixes and address summarization.

5. Why are reserved VLANs included?

Reserved VLANs help you plan for guest access, voice traffic, management networks, testing zones, or future departments without renumbering later.

6. What if capacity status fails?

A failed status means the base network cannot fit the requested number of segments at the recommended subnet size. Use a larger base block.

7. Can I use this for branch offices?

Yes. It works well for branch planning, campus segmentation, lab environments, and internal zone design where predictable IPv4 allocation matters.

8. What does the chart show?

The chart visualizes planned hosts per segment, making it easier to compare zone sizes and identify heavily loaded or lightly used network segments.