IP Range Calculator - Subnet CIDR Calculator Free

How to Use the IP Range Calculator

1. Enter CIDR notation — type an IPv4 address with CIDR suffix (e.g., 192.168.1.0/24 or 10.0.0.0/16)
2. View network details — instantly see the network address, broadcast address, first usable IP, and last usable IP
3. Check host count — total and usable hosts in the subnet
4. See subnet mask — dotted decimal subnet mask and wildcard mask
5. Review binary — binary representation of the network address

Features

• Network & broadcast addresses — calculated precisely from CIDR notation
• Usable IP range — first to last usable host address
• Host count — total IPs and usable IPs (automatically subtracts network and broadcast addresses)
• Subnet mask & wildcard — shown in standard dotted decimal notation
• Binary representation — network address displayed in binary for learning
• IP class detection — identifies Class A through E

Use Cases

• Network planning: When designing a new subnet, calculate exactly how many usable addresses you’ll have
• AWS/VPC configuration: AWS requires CIDR blocks for VPCs and subnets — verify your chosen block has enough IPs
• Firewall rules: Understanding the IP range helps write precise firewall allow/deny rules
• VPN configuration: Set up correct subnet masks for VPN tunnels to avoid routing conflicts
• CCNA studying: Networking students use CIDR calculators to verify their subnetting homework

FAQ

What does the /24 mean in 192.168.1.0/24?

The /24 is the CIDR prefix length — it tells you how many bits are used for the network portion. A /24 means 24 bits for the network and 8 bits for hosts, giving 254 usable IP addresses. Common values are /8, /16, /24, and /32.

Why aren’t all IPs in a subnet usable?

Each subnet reserves the first address as the network address and the last address as the broadcast address. For example, in 192.168.1.0/24, 192.168.1.0 is the network and 192.168.1.255 is the broadcast — only .1 through .254 are usable.

What’s the difference between a subnet mask and CIDR?

They express the same thing in different formats. CIDR notation (/24) is the modern, compact form. The subnet mask (255.255.255.0) is the traditional dotted-decimal form. This tool shows both.

What CIDR should I use for a home network?

A /24 network (255.255.255.0 mask) gives you 254 usable addresses, which is plenty for a typical home or small office network. Use a /16 if you need more than 254 devices on the same network.

Tips

• Always reserve a few IPs beyond your calculated need — you’ll thank yourself later when adding devices
• For point-to-point links (two routers), use /30 (2 usable IPs) or /31 (if your equipment supports RFC 3021)
• When planning VLANs, standardize on a few CIDR sizes (/24, /25, /26) to keep things simple