🌐 Subnet Calculator
Calculate IP subnets, network addresses, broadcast addresses, and host ranges for network planning.
Common Subnet Masks
/24
255.255.255.0
254 hosts
/25
255.255.255.128
126 hosts
/26
255.255.255.192
62 hosts
/27
255.255.255.224
30 hosts
/28
255.255.255.240
14 hosts
/30
255.255.255.252
2 hosts
Subnet Calculator Features
🔧 Multiple Input Methods
Calculate subnets using CIDR notation, subnet masks, or required host count. Flexible input for different networking scenarios.
📊 Complete Analysis
Get network address, broadcast address, host ranges, and binary representations for comprehensive subnet planning.
🌐 Network Planning
Perfect for network administrators, students, and IT professionals planning IP address allocations and network segmentation.
Subnet Calculator FAQ
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation shows an IP address followed by a slash and number indicating network bits. For example, 192.168.1.0/24 means 24 bits are used for the network portion.
How do I choose the right subnet size?
Consider the number of hosts needed in each subnet. Choose the smallest subnet that accommodates your hosts plus growth. Remember that 2 addresses (network and broadcast) are not usable for hosts.
What's the difference between network and broadcast addresses?
The network address (all host bits 0) identifies the subnet itself. The broadcast address (all host bits 1) is used to send data to all devices in the subnet. Neither can be assigned to hosts.
What is a wildcard mask?
A wildcard mask is the inverse of a subnet mask. It's used in access control lists (ACLs) and routing protocols. Where subnet mask has 1s, wildcard mask has 0s, and vice versa.
When to Use This Calculator
Use this when designing or troubleshooting a network, allocating IP address ranges to departments, verifying subnet masks, or studying for CCNA and other networking certifications.
Common Mistakes to Avoid
- Confusing CIDR notation with subnet mask — /24 equals a subnet mask of 255.255.255.0; both describe the same network boundary.
- Forgetting to reserve the network and broadcast addresses — a /24 subnet has 254 usable host addresses, not 256.
- Using overlapping subnets — overlapping IP ranges cause routing conflicts; always verify that subnets do not share any address space.