How to Choose the Right IPv4 Subnet Size for Your Network
Choosing the right IPv4 subnet size is one of the most important decisions for network planning, resource allocation, and long-term scalability. Whether you’re an ISP, hosting provider, enterprise network engineer, or cloud architect, the subnet size you select determines how efficiently your network operates and how well it can grow. With IPv4 scarcity and rising IP prices, selecting the correct block size has become more critical than ever.
This guide explains how different subnet sizes work, what factors influence your choice, and how to match your network requirements to the most cost-effective and scalable IPv4 block.
Understanding Common IPv4 Subnet Sizes
IPv4 blocks are typically allocated in CIDR notation. The most commonly leased or purchased subnet sizes include:
/24 (256 IPs)
- Ideal for small hosting setups, VPNs, startups, and isolated environments
- Easy to route globally
- Most carriers and cloud providers accept /24 as the smallest routed block
/23 (512 IPs)
- Suitable for growing businesses or networks with expanding customer bases
- More cost-efficient per IP compared to a /24
- Useful for ISPs and regional hosting providers
/22 (1024 IPs)
- Good for large customer deployments, data centers, and high-volume networks
- Reduces fragmentation by consolidating multiple /24s
- Helps simplify routing and minimize overhead
/21 (2048 IPs)
- Used by ISPs, infrastructure providers, and enterprises with large traffic demands
- Provides long-term headroom without frequent subnet upgrades
- More favorable economics in bulk pricing
Key Factors When Choosing the Right Subnet Size
1. Current Number of Devices or Users
Your subnet must accommodate your present network needs. Overestimating wastes IP resources; underestimating forces future block changes.
2. Expected Growth Over 12–36 Months
Think ahead, scaling by combining multiple smaller blocks can create routing complexity. A single larger block often delivers better efficiency.
3. Routing Policies and Upstream Requirements
Some carriers won’t announce blocks smaller than a /24.
ISPs and data centers should confirm routing policies before choosing a subnet.
4. Security Segmentation Needs
Smaller subnets offer better isolation for:
- Customer environments
- Departments
- Services with different security requirements
Larger subnets can simplify management but may require advanced segmentation tools.
5. Budget and Market Pricing
IPv4 pricing increases as block size decreases.
Examples:
- A /24 costs more per IP
- A /21 or /22 offers bulk discounts
Your budget may influence whether you choose a single large block or multiple small ones.
Subnet Size Recommendations by Use Case
For Hosting Providers
Start with a /23 or /22, enough space to grow while maintaining routing efficiency.
For VPN or SaaS Platforms
A /24 usually meets the requirement and is widely accepted for global routing.
For ISPs and Carrier Networks
A /21 or larger provides the stability and scalability necessary for customer growth.
For Enterprise Internal Networks
A mix of /24 segments for departments and services helps maintain strong security boundaries.
About IPv4Hub.net
When choosing the right IPv4 subnet size, partnering with a reliable provider is essential. IPv4Hub.net helps businesses lease clean, verified IP blocks of any size, from /24 to /21 and beyond. Every block undergoes blacklist checks, reputation validation, and registry verification before delivery. IPv4Hub.net also assists with documentation, routing setup, LOA support, and RPKI configuration, ensuring that networks can deploy IP space quickly and securely. Whether you’re scaling infrastructure or planning long-term IP needs, IPv4Hub.net offers human-powered guidance and trusted IPv4 leasing solutions. Explore IPv4 Categories.
Selecting the correct IPv4 subnet size is a strategic decision that affects network performance, growth potential, security, and cost efficiency. By assessing your current requirements, anticipating future expansion, and understanding routing and pricing implications, you can choose a subnet that supports your long-term goals. With expert partners like IPv4Hub.net, businesses can confidently obtain IP blocks that align with both operational needs and budget constraints.