CIDR Prefix: /21
Usable Host Range for /21 Subnet
Medium-to-large availability zone subnet supporting up to 2,046 compute instances. Pre-calculated routing boundaries, binary mapping mask, cloud provider allocation metrics, and copy-ready Terraform snippets.
100% Free & Secure Client-Side Sandbox
Interactive /21 Subnet Workspace
Pre-loaded Seed: 10.0.0.0/21Instantly ingest standardized industrial address space assignments from cloud reference blueprints.
Pre-Computed /21 Subnet Technical Specifications
Verified 32-bit Bitwise Calculation MatrixSubnet Mask (Dotted Decimal)255.255.248.0
Usable Host Capacity2,046 IPs
Cloud Reserved IPs (AWS)5 IPs
Default Range Seed10.0.0.0/21
| Binary Mask Blueprint | 11111111.11111111.11111000.00000000 |
|---|---|
| CIDR Notation | /21 |
| Netmask Address | 255.255.248.0 |
| Total Host Addresses | 2,048 |
| Usable Hosts (Standard IPv4) | 2,046 usable IPs |
| Cloud Net Capacity (AWS / GCP) | 2,043 usable IPs(AWS reserves 5 addresses: Network, VPC Router, DNS, Reserved, Broadcast) |
| Primary Architectural Use Case | Medium-to-large availability zone subnet supporting up to 2,046 compute instances. |
Terraform IaC Configuration Block (/21)
Copy-ready infrastructure coderesource "aws_subnet" "subnet_21" {
vpc_id = aws_vpc.main.id
cidr_block = "10.0.0.0/21"
availability_zone = "us-east-1a"
tags = {
Name = "app-tier-21"
}
}Related CIDR Subnet Specifications
← Larger Network (Double Host Capacity)/20 Subnet (4,094 Usable Hosts)
GCP default custom VNet block and standard large availability zone subnet.
Smaller Network (Half Host Capacity) →/22 Subnet (1,022 Usable Hosts)
Standard subnet size for container orchestrators and enterprise application clusters.