IP Subnet Calculator

IP Subnet Calculator – CIDR, Subnet Mask, Hosts, Wildcard & Network Ranges

The IP Subnet Calculator on MyTimeCalculator is a professional-grade IPv4 networking tool that allows you to instantly calculate subnet details using CIDR notation, IP address with subnet mask, or subnet splitting. It is designed for network engineers, IT students, system administrators, cybersecurity professionals, cloud architects, and anyone working with computer networks.

With this calculator, you can quickly determine:

• Network address
• Broadcast address
• First and last usable host
• Subnet mask and wildcard mask
• Total IP addresses and usable hosts
• IP class and length
• Split large networks into smaller subnets

Instead of memorizing subnetting tables or performing binary math manually, this tool produces instant, error-free results for real-world network design, certification preparation (CCNA, CCNP), enterprise networking, home labs, and cloud infrastructure.

What Is an IP Subnet?

An IP subnet is a logical subdivision of a larger IP network. Subnetting allows a large IP address space to be divided into smaller, more efficient networks. This improves:

• Network performance
• Security and access control
• Traffic management
• Efficient IP address utilization
• Scalability of enterprise networks

In IPv4, every subnet is defined by:

• An IP address
• A length (CIDR)
• Or a subnet mask (dotted decimal format)

What Is CIDR Notation?

CIDR (Classless Inter-Domain Routing) is a modern IP addressing scheme that replaces the older class-based system. Instead of rigid Class A, B, and C networks, CIDR allows flexible lengths from /0 to /32.

The number after the slash represents how many bits are used for the network portion:

• /8 → 8 network bits
• /16 → 16 network bits
• /24 → 24 network bits
• /30 → 30 network bits
• /32 → Single host

Your IP Subnet Calculator instantly converts CIDR notation into:

• Dotted decimal subnet mask
• Wildcard mask
• Network boundary
• Broadcast address
• Usable host range

Subnet Mask Explained (Dotted Decimal)

A subnet mask determines which part of an IP address is the network and which part is the host. It is written in dotted decimal format like:

• 255.0.0.0
• 255.255.0.0
• 255.255.255.0

Each “255” represents 8 network bits (11111111 in binary). Your calculator automatically maps each CIDR to its correct subnet mask.

Wildcard Mask Explained

A wildcard mask is the inverse of a subnet mask. It is commonly used in:

• Access Control Lists (ACLs)
• Firewall rules
• Routing filters

Example:

Your IP Subnet Calculator generates wildcard masks automatically.

Network Address, Broadcast Address & Host Range

Network Address

The network address is the first address in a subnet. It identifies the subnet itself and cannot be assigned to a device.

Broadcast Address

The broadcast address is the last address in a subnet. It is used to send packets to all hosts in that subnet.

Usable Host Range

The range between the network and broadcast addresses contains the usable IP addresses that can be assigned to computers, routers, servers, and firewalls.

Total Addresses vs Usable Hosts

Total addresses in a subnet are calculated as:

Usable hosts are typically:

Exceptions:

• /31 networks use both IPs (point-to-point links)
• /32 networks represent a single IP only

IP Address Classes

Although CIDR is now the standard, IPv4 addresses still fall into traditional classes:

• Class A: 1.0.0.0 – 126.255.255.255
• Class B: 128.0.0.0 – 191.255.255.255
• Class C: 192.0.0.0 – 223.255.255.255
• Class D: Multicast
• Class E: Reserved

Your calculator automatically identifies the class of any IPv4 address.

Subnet Splitter – Divide a Large Network Easily

The Subnet Splitter mode allows you to divide a large network into:

• A specific number of subnets
• Or subnets with a fixed number of hosts

Example

Starting with:

Splitting into 4 subnets produces:

• 192.168.0.0/26
• 192.168.0.64/26
• 192.168.0.128/26
• 192.168.0.192/26

Each of these has 62 usable hosts.

VLSM (Variable Length Subnet Masking)

VLSM allows different subnet sizes within the same network. This is essential for:

• Enterprise VLAN design
• Cloud infrastructure
• Data centers
• ISP address allocation

Your subnet calculator supports host-based subnet calculations, which is the foundation of VLSM planning.

Where IP Subnet Calculators Are Used

• Enterprise network design
• Firewall and ACL configuration
• Cloud networking (AWS, Azure, GCP)
• Home labs and virtualization
• ISP and telecom networks
• Cybersecurity segmentation
• University and IT certification labs

Why Use an Online IP Subnet Calculator?

• No manual binary conversion
• No subnet tables required
• Works instantly on mobile and desktop
• Error-free results
• Multiple calculation modes
• Free & unlimited usage

Accuracy & Security

All subnet calculations are performed locally in your browser. No IP data is stored on any server. Your network designs remain completely private.

Learn Networking with Confidence

This IP Subnet Calculator is ideal for:

• CCNA students
• Network administrators
• DevOps engineers
• Penetration testers
• IT instructors