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Common Private Subnet Examples (By Subnet Size)

Common Private Subnet Examples by CIDR Size

Overview
Subnetting is one of the most important skills in networking. But most training materials only explain the math — not the real-world examples. This CSV provides real, practical examples of private subnets at multiple common CIDR sizes.

Unlike generic subnetting charts, this table includes:

  • Actual private IP blocks
  • Network address
  • Gateway address
  • Broadcast address
  • First and last usable host
  • Total and usable host counts
  • Subnet class
  • Detailed usage notes (what each subnet size is typically used for)

This transforms subnetting from an academic exercise into a practical engineering reference.

What This CSV Contains

For each example subnet (e.g., /20, /21, /22, /23, /24, /25, /26, … /32) you get:

  • Example subnet CIDR
  • Prefix length
  • Private range membership
  • Class (A/B/C)
  • Network address
  • Gateway (.1)
  • Broadcast
  • First usable
  • Last usable
  • Total addresses
  • Usable addresses
  • Real-world usage notes (e.g., “Great for WiFi pools”, “Ideal for IoT segmentation”, “Point-to-point link”)

Why This Matters

Engineers often struggle with:

  • Knowing which subnet size to use
  • Understanding the right tool for the job
  • Designing networks with best practices
  • Deciding between /23 vs /24 vs /25
  • Learning how broadcast and gateway positions change with subnet size

This table becomes a reference hub for network design.

You can use this on your site as:

  • A subnetting tutorial
  • A design guide
  • A conversion helper
  • A VLAN sizing reference

 

Edit
Example Subnet (CIDR)Prefix LengthPrivate RangeClassNetwork AddressGateway IP (Example)Broadcast AddressFirst Usable HostLast Usable HostTotal AddressesUsable HostsNotes
10.0.0.0/8810.0.0.0/8A10.0.0.010.0.0.110.255.255.25510.0.0.110.255.255.2541677721616777214Very large private networks; often ISP cores, large enterprises, or big internal address plans (10.0.0.0/8).
172.16.0.0/1212172.16.0.0/12B172.16.0.0172.16.0.1172.31.255.255172.16.0.1172.31.255.25410485761048574Private aggregation for multiple sites or departments (172.16.0.0/12); often split into /16-/24 blocks.
192.168.0.0/1616192.168.0.0/16C192.168.0.0192.168.0.1192.168.255.255192.168.0.1192.168.255.2546553665534Common for large campus or multi-department LANs; often further subnetted into /24s (192.168.0.0/16).
10.0.0.0/202010.0.0.0/8A10.0.0.010.0.0.110.0.15.25510.0.0.110.0.15.25440964094Good for medium-sized segments, shared services, or container/VM clusters (≈4094 usable hosts).
10.0.8.0/212110.0.0.0/8A10.0.8.010.0.8.110.0.15.25510.0.8.110.0.15.25420482046Used for large WiFi pools, guest networks, or dense IoT segments (≈2046 usable hosts).
192.168.0.0/2222192.168.0.0/16C192.168.0.0192.168.0.1192.168.3.255192.168.0.1192.168.3.25410241022Common in data centers or large VLANs where ~1000 hosts are needed (≈1022 usable hosts).
192.168.0.0/2323192.168.0.0/16C192.168.0.0192.168.0.1192.168.1.255192.168.0.1192.168.1.254512510Popular for large access VLANs, WiFi, or combined segments needing ~500 hosts (≈510 usable hosts).
192.168.0.0/2424192.168.0.0/16C192.168.0.0192.168.0.1192.168.0.255192.168.0.1192.168.0.254256254Standard LAN size; typical office, lab, or VLAN network (254 usable hosts).
192.168.0.0/2525192.168.0.0/16C192.168.0.0192.168.0.1192.168.0.127192.168.0.1192.168.0.126128126Smaller secured segments like management, desktops vs. servers, or separated user groups (126 usable hosts).
192.168.0.0/2626192.168.0.0/16C192.168.0.0192.168.0.1192.168.0.63192.168.0.1192.168.0.626462Voice VLANs, cameras, or tightly-scoped access networks (62 usable hosts).
192.168.0.0/2727192.168.0.0/16C192.168.0.0192.168.0.1192.168.0.31192.168.0.1192.168.0.303230Small device groups, labs, or IoT segments (30 usable hosts).
192.168.0.0/2828192.168.0.0/16C192.168.0.0192.168.0.1192.168.0.15192.168.0.1192.168.0.141614Very small segments—testing, out-of-band, or small device clusters (14 usable hosts).
192.168.0.0/2929192.168.0.0/16C192.168.0.0192.168.0.1192.168.0.7192.168.0.1192.168.0.686WAN edges, firewall transit networks, or tiny infrastructure segments (6 usable hosts).
192.168.0.0/3030192.168.0.0/16C192.168.0.0192.168.0.1192.168.0.3192.168.0.1192.168.0.242Classic point-to-point link size (2 usable hosts).
192.168.0.0/3131192.168.0.0/16C192.168.0.0192.168.0.0N/A192.168.0.0192.168.0.122Modern point-to-point links per RFC 3021; both addresses are usable, no broadcast.
192.168.0.10/3232192.168.0.0/16C192.168.0.10192.168.0.10N/A192.168.0.10192.168.0.1011Single host assignment—loopbacks, VIPs, or device-specific addresses.