Subnet Table Generator
Create a structured addressing reference.
Subnet Table Generator: inputs and results
Enter an IP address, CIDR prefix, or range. Then check its first and last address below.
Calculated Boundaries & ParametersReady
Key Capabilities
- •100% Client-Side: Zero telemetry or server latency.
- •RFC Compliant: Exact 32-bit and 128-bit integer precision.
- •Quick Copy: Instant access to CIDR, mask, and range bounds.
- •Cross-Platform: Works on desktop, tablet, and mobile browsers.
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How Subnet Table Generator Works?
This tool works by dividing a parent block into subnets of a chosen size and writing 1 complete reference row per subnet: network, mask, wildcard, gateway, host range, and broadcast.
Enter the parent block
Type the block, such as
10.10.0.0/22.Choose the subnet size
Pick the child prefix, such as
/24.Choose the columns
Select the fields to include: mask, wildcard, gateway, host range, broadcast, and host count.
Export the table
The table downloads as CSV, Markdown, or HTML for documentation.
Subnet Table Generator Formula
The formula is Row_k = Parent + k × 2^(32 − c), with Gateway_k = Row_k + 1 and Broadcast_k = Row_k + 2^(32 − c) − 1.
Row count
2^(c − p)Subnets in the table.
Network of row k
N + k × 2^(32−c)k from 0.
Gateway convention
Network + 1First usable host.
Wildcard
255.255.255.255 − MaskFor ACL columns.
Worked example: 10.10.0.0/22 into /24
Rows = 2^(24 − 22) = 4 Row 1: 10.10.0.0/24 gateway 10.10.0.1 broadcast 10.10.0.255 Row 4: 10.10.3.0/24 gateway 10.10.3.1 broadcast 10.10.3.255
Subnet Table Generator Conversion Table
The table is a full reference table for 10.10.0.0/22 divided into 4 /24 subnets.
| Subnet | Mask | Wildcard | Gateway | Host Range | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 10.10.0.0/24 | 255.255.255.0 | 0.0.0.255 | 10.10.0.1 | 10.10.0.2 – 10.10.0.254 | 10.10.0.255 | 254 |
| 10.10.1.0/24 | 255.255.255.0 | 0.0.0.255 | 10.10.1.1 | 10.10.1.2 – 10.10.1.254 | 10.10.1.255 | 254 |
| 10.10.2.0/24 | 255.255.255.0 | 0.0.0.255 | 10.10.2.1 | 10.10.2.2 – 10.10.2.254 | 10.10.2.255 | 254 |
| 10.10.3.0/24 | 255.255.255.0 | 0.0.0.255 | 10.10.3.1 | 10.10.3.2 – 10.10.3.254 | 10.10.3.255 | 254 |
The host range starts after the gateway (.1), so each row lists .2 to .254.
What is Subnet Table Generator?
The Subnet Table Generator is a tool that produces a structured reference table for every subnet in an address block, ready to drop into documentation.
Network documentation needs the same columns for every subnet. Writing them by hand invites copy errors in masks, wildcards, and broadcasts. The generator fills every column from the same calculation, so the whole table stays consistent.
The table works as a quick reference for field engineers, who look up the gateway and mask of a subnet without running a calculator.
What are the uses of Subnet Table Generator?
There are 4 main uses of the Subnet Table Generator, including site documentation, runbooks, and configuration templates.
Documenting sites
Each site wiki page carries a full subnet table.
Writing runbooks
Field technicians use the table to configure devices without calculation.
Feeding configuration templates
CSV output drives templated switch and router configuration.
Printing reference sheets
Printed tables sit in network rooms for quick lookup.