ℹ️ Over 50,000 network engineers, sysadmins, and students use this subnet calculator 2026. Get instant IPv4 network address, broadcast, usable hosts, wildcard mask, and CIDR conversion.
📊 Formula: Total Addresses = 2^(32−CIDR) | Usable Hosts = Total − 2 | Network = IP AND Mask | Broadcast = Network OR Wildcard Mask
💡 Tip: If you need more than 254 devices on one network segment, use /23 (510 hosts) or larger instead of /24.
✅ "Perfect for subnetting practice. Confirmed my hand calculations matched the tool!"
What is a Subnet Calculator and How Does It Work?
A subnet calculator is an essential network administration tool that analyzes an IPv4 address and CIDR prefix to determine the full subnet boundary. Our subnet calculator 2026 answers the core questions every network engineer, sysadmin, and student needs: What is the network address? What is the broadcast address? How many usable hosts are available? What is the usable IP range?
How does the IPv4 subnet calculator work? Enter an IP address (e.g., 192.168.1.10) and a CIDR prefix (e.g., /24). The calculator converts the CIDR to a subnet mask, performs bitwise AND to find the network address, calculates the broadcast address using the wildcard mask, and derives the usable host range. The CIDR calculator also shows total addresses, subnet class, and whether the IP is private or public.
Usable Hosts = 2^(32 − CIDR) − 2. Example: /24 → 256 − 2 = 254 hosts. The two subtracted addresses are the network and broadcast addresses.
Network Address = IP AND Subnet Mask. Example: 192.168.1.10 AND 255.255.255.0 = 192.168.1.0.
Broadcast Address = Network OR Wildcard Mask. Example: 192.168.1.0 OR 0.0.0.255 = 192.168.1.255.
First Usable Host = Network + 1 = 192.168.1.1.
Last Usable Host = Broadcast − 1 = 192.168.1.254.
Understanding CIDR Notation
CIDR (Classless Inter-Domain Routing) notation uses a slash and a number to indicate the number of network bits in a subnet mask. A /24 means the first 24 bits of the 32-bit IPv4 address are the network portion. The remaining 8 bits are host bits, giving 2^8 = 256 total addresses and 254 usable hosts.
Common CIDR values you'll encounter in real networks: /30 for point-to-point WAN links (2 usable hosts), /29 for small server segments (6 hosts), /27 for small offices (30 hosts), /24 for standard office LANs (254 hosts), and /16 for enterprise campus networks (65,534 hosts).
Private vs Public IP Addresses
Private IP ranges (RFC 1918) are reserved for internal networks and are not routable on the public internet:
10.0.0.0/8 — 16,777,216 addresses
172.16.0.0/12 — 1,048,576 addresses
192.168.0.0/16 — 65,536 addresses
All other IPv4 addresses are public (globally routable) unless they fall in reserved/loopback/link-local ranges. The subnet calculator identifies the IP type automatically.
IP Classes (Historical)
Class A: 1.0.0.0 – 126.255.255.255 (default /8). Class B: 128.0.0.0 – 191.255.255.255 (default /16). Class C: 192.0.0.0 – 223.255.255.255 (default /24). Class D: 224.0.0.0 – 239.255.255.255 (multicast). Class E: 240.0.0.0 – 255.255.255.255 (experimental). Modern networks use CIDR and ignore these classes, but the calculator still identifies the class for historical reference.
Wildcard Masks
The wildcard mask is the inverse of the subnet mask and is used in ACLs (Access Control Lists) on Cisco routers and firewalls. For /24 (255.255.255.0), the wildcard mask is 0.0.0.255. The subnet calculator displays this automatically — essential for network security configuration.
Special CIDR Cases
/31 (RFC 3021): 2 usable hosts (both addresses usable, no broadcast). Ideal for point-to-point links where you want to conserve IPs.
/32: A single host — used for loopback addresses and host routes.
/30: The traditional choice for point-to-point WAN links with 2 usable hosts (network and broadcast are reserved).
❓ Frequently Asked Questions
How do I calculate a subnet?
Enter your IPv4 address and CIDR prefix (0-32). The subnet calculator finds the network address (IP AND mask), broadcast address, usable host range, and total hosts using 2^(32-CIDR) - 2 formula.
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) is written as /n where n is the number of network bits. /24 = 255.255.255.0 (254 usable hosts). /16 = 255.255.0.0 (65,534 hosts). /30 = 255.255.255.252 (2 usable hosts, ideal for point-to-point links).
How many usable hosts are in a /24 subnet?
A /24 subnet has 256 total addresses, 254 usable hosts (256 - network - broadcast). Formula: 2^(32-24) - 2 = 2^8 - 2 = 254.
What is the difference between network and broadcast address?
The network address (all host bits = 0) identifies the subnet itself and cannot be assigned to a host. The broadcast address (all host bits = 1) sends data to all devices in the subnet and also cannot be assigned.
What is a /30 subnet used for?
/30 provides 2 usable hosts and is commonly used for point-to-point WAN links between routers where only two endpoints need addressing.
What is the subnet mask for /26?
/26 subnet mask is 255.255.255.192. It provides 64 total addresses, 62 usable hosts (2^6 - 2 = 62). The block size is 64 in the last octet.
💡 Expert Tips for Subnetting
Tip #1: Always verify the network and broadcast addresses before configuring DHCP scopes. Assigning them to hosts causes conflicts.
Tip #2: Use /30 for point-to-point links between routers. Only /31 (RFC 3021) gives you both addresses, but /30 is more widely supported.
Tip #3: For IoT devices or segmented VLANs, use /27 or /28 to conserve public IP space and improve security.
Tip #4: Bookmark your subnets using the wildcard mask — essential when configuring ACLs and firewall rules.
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🛡️ CDCalculators proprietary subnet calculator 2026 — data sources: IANA IPv4 registry, RFC 1918, RFC 3021, RFC 4632. Last updated October 22, 2026. Disclaimer: Educational tool. Always verify production network configurations.