Subnet Calculator

Calculate IP subnets with CIDR notation, subnet masks, and network information

IP Address & Subnet

IP Address

CIDR Notation

/24

Split Subnet

Network Information

Network Address192.168.1.0

Broadcast Address192.168.1.255

First Usable IP192.168.1.1

Last Usable IP192.168.1.254

Usable Hosts254

Total Hosts256

Subnet Mask255.255.255.0

Wildcard Mask0.0.0.255

IP ClassClass C

IP Type Private

CIDR Notation192.168.1.0/24

IP Range192.168.1.0 - 192.168.1.255

CIDR Quick Reference

CIDRSubnet MaskWildcardUsable Hosts

Subnet Calculator - IP Subnet, CIDR, Network Calculator | Free Tool

Professional subnet calculator with CIDR notation support. Calculate IP subnets, network addresses, broadcast addresses, usable hosts, and subnet masks. Includes subnet splitting and VLSM support.

Features

Calculate IPv4 subnets with CIDR notation and subnet mask support
Instant network address and broadcast address calculation
Automatic calculation of total hosts and usable hosts
Binary representation showing IP, mask, and network in binary
IP class detection (Class A, B, C, D, E) with visual indicators
Private and public IP identification (RFC 1918 ranges)
Wildcard mask calculation for Cisco ACLs
Subnet splitting tool with VLSM support
CIDR quick reference table (/8 to /32)
Subnet mask and CIDR converter
Network range validator
Copy results to clipboard
Real-time validation and error messages
Dark and light theme support

How to use

Enter IP address in dotted decimal notation like 192.168.1.0
Specify subnet using CIDR slash notation or subnet mask
Click Calculate to compute network information instantly
View network address, broadcast, and usable IP range
Check IP class and type (Public, Private, etc.)
Examine binary representation to understand bit-level subnetting
Use subnet splitting to divide network into smaller subnets
Reference CIDR table for quick subnet mask lookup
Copy results for documentation
Validate subnet calculations

Tips & Best Practices

Double-check URLs and hostnames before running network lookups.
Results may vary based on DNS propagation and network conditions.
Use this tool for debugging and development, not for production monitoring.
Some checks may be blocked by firewalls or CORS policies.
All lookups are performed client-side when possible for privacy.

FAQ

What is CIDR notation and how does it work?

CIDR (Classless Inter-Domain Routing) notation uses a slash followed by the number of network bits. For example, /24 means the first 24 bits are the network portion, leaving 8 bits for hosts (256 total IPs). CIDR replaced classful addressing allowing flexible network sizing.

What are private IP addresses?

Private IPs (RFC 1918) are: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These are for internal networks only and require NAT to access the Internet. They can be reused by different organizations without conflict.

Why are there 2 fewer usable hosts than total hosts?

Two addresses are reserved: network address (all host bits 0) and broadcast address (all host bits 1). For example, /24 has 256 total addresses but only 254 usable (network .0 and broadcast .255 are reserved).

Is this tool free to use?

Yes, this tool is completely free with no registration required. There are no usage limits, no premium tiers, and no hidden costs. You can use it as many times as you need.

Is my data safe and private?

Absolutely. All processing happens locally in your browser. No data is ever sent to our servers or any third party. Your input never leaves your device, making it completely safe for sensitive information.