IPv4 • IPv6 • CIDR • IP Ranges

Free IPv4 and IPv6 Subnet Calculator

Free, instant, in-browser subnet calculator for IPv4 and IPv6 networks. Calculate network addresses, usable host ranges, subnet masks, CIDR prefixes, and broadcast addresses with real-time 32-bit binary breakdown and zero latency.

IP Subnet Calculator & CIDR Range Console

/24

Target IP Address or CIDR (e.g. 192.168.1.1 or 10.0.0.1/24)

Subnet Mask & Netmask Prefix

Prefix: /24Mask: 255.255.255.0

Quick Presets:

32-Bit Register Matrix

Net (24) Host (8)

Octet

1286432168421

Mask

Click any bit above to set prefix boundary interactively.

IPv4 Subnet & IP Range Summary:192.168.1.1/24

Network Address:

192.168.1.0

Broadcast Address:

192.168.1.255

Subnet Mask:

255.255.255.0(Hex: 0xFFFFFF00 )

Wildcard Mask:

0.0.0.255

Start address:

192.168.1.1

End Address:

192.168.1.254

Usable Host Range:

192.168.1.1-192.168.1.254

Usable Hosts:

254(Total: 256)

Class & Type:

Class C (Private Network (RFC 1918))

Binary Network:

11000000.10101000.00000001.00000000

Binary Mask:

11111111.11111111.11111111.00000000

Reverse DNS (PTR):

1.1.168.192.in-addr.arpa

IP Integer & Hex:

3232235777(Hex: 0xC0A80101 )

IPv4-Mapped IPv6:

::ffff:192.168.1.1

Subnet Divider, VLAN Calculator & CIDR Range Slicer

VLAN & VPC Sizing

Carve any parent IP CIDR block into equal child subnets, VLANs, and cloud IP ranges with network wire IDs, usable host ranges, and broadcast boundaries.

Parent Network IP

Parent Prefix

Target Subnet Size (Prefix)

Dividing /24 into 4 subnets of /26 (62 usable hosts each)

Scroll horizontally →

#	Subnet CIDR	Subnet Mask	Usable Host Range	Broadcast Address	Usable Hosts

CIDR Subnet Table, Subnet Mask Chart & Prefix Lengths (/0 — /32)

Complete reference cheat sheet for subnet masks, netmasks, wildcard masks, and usable IP address ranges.

Scroll horizontally →

CIDR	Subnet Mask	Wildcard Mask	Total Addresses	Usable Hosts	Standard Application
/32	255.255.255.255	0.0.0.0	1	1	Single Host / Loopback / VPN endpoint
/31	255.255.255.254	0.0.0.1	2	2	Modern Point-to-Point Links (2 hosts)
/30	255.255.255.252	0.0.0.3	4	2	Legacy Point-to-Point Links (2 hosts)
/29	255.255.255.248	0.0.0.7	8	6	ISP Public Blocks (6 hosts) - HA Firewalls
/28	255.255.255.240	0.0.0.15	16	14	Sixteenth /24 (14 hosts) - DMZ / Server subnets
/27	255.255.255.224	0.0.0.31	32	30	Eighth /24 (30 hosts) - Small VLANs
/26	255.255.255.192	0.0.0.63	64	62	Quarter /24 (62 hosts) - Departments / VLANs
/25	255.255.255.128	0.0.0.127	128	126	Half /24 (126 hosts) - Branch Offices
/24	255.255.255.0	0.0.0.255	256	254	Standard Class C LAN block (254 hosts)
/23	255.255.254.0	0.0.1.255	512	510	CIDR prefix allocation (/{c})
/22	255.255.252.0	0.0.3.255	1,024	1,022	CIDR prefix allocation (/{c})
/21	255.255.248.0	0.0.7.255	2,048	2,046	CIDR prefix allocation (/{c})
/20	255.255.240.0	0.0.15.255	4,096	4,094	CIDR prefix allocation (/{c})
/19	255.255.224.0	0.0.31.255	8,192	8,190	CIDR prefix allocation (/{c})
/18	255.255.192.0	0.0.63.255	16,384	16,382	CIDR prefix allocation (/{c})
/17	255.255.128.0	0.0.127.255	32,768	32,766	CIDR prefix allocation (/{c})
/16	255.255.0.0	0.0.255.255	65,536	65,534	Historic Class B network (65,534 hosts)
/15	255.254.0.0	0.1.255.255	131,072	131,070	CIDR prefix allocation (/{c})
/14	255.252.0.0	0.3.255.255	262,144	262,142	CIDR prefix allocation (/{c})
/13	255.248.0.0	0.7.255.255	524,288	524,286	CIDR prefix allocation (/{c})
/12	255.240.0.0	0.15.255.255	1,048,576	1,048,574	RFC 1918 Class B Private Block (172.16.0.0/12)
/11	255.224.0.0	0.31.255.255	2,097,152	2,097,150	CIDR prefix allocation (/{c})
/10	255.192.0.0	0.63.255.255	4,194,304	4,194,302	CIDR prefix allocation (/{c})
/9	255.128.0.0	0.127.255.255	8,388,608	8,388,606	CIDR prefix allocation (/{c})
/8	255.0.0.0	0.255.255.255	16,777,216	16,777,214	Historic Class A network (16.7M hosts)
/7	254.0.0.0	1.255.255.255	33,554,432	33,554,430	CIDR prefix allocation (/{c})
/6	252.0.0.0	3.255.255.255	67,108,864	67,108,862	CIDR prefix allocation (/{c})
/5	248.0.0.0	7.255.255.255	134,217,728	134,217,726	CIDR prefix allocation (/{c})
/4	240.0.0.0	15.255.255.255	268,435,456	268,435,454	CIDR prefix allocation (/{c})
/3	224.0.0.0	31.255.255.255	536,870,912	536,870,910	CIDR prefix allocation (/{c})
/2	192.0.0.0	63.255.255.255	1,073,741,824	1,073,741,822	CIDR prefix allocation (/{c})
/1	128.0.0.0	127.255.255.255	2,147,483,648	2,147,483,646	1/2 of Internet Address Space
/0	0.0.0.0	255.255.255.255	4,294,967,296	4,294,967,294	Default Route (Entire Internet 0.0.0.0/0)

RFC Protocol Specification & Architecture

IP Subnet Architecture & Bitwise Engineering Guide

Deep technical documentation on bitwise Boolean masks, CIDR network boundaries, usable IP range subnet rules, and IETF RFC standards.

01 // CONCEPTS

What is Subnetting and Why Use an Online Bitwise Engine?

Subnetting is the logical segmentation of a physical or cloud IP network into smaller, isolated broadcast domains (subnets). Using a bitwise calculator eliminates human arithmetic errors when sizing AWS VPCs, Azure VNets, Google Cloud VPCs, and enterprise VLANs.

Broadcast Containment

Restricts ARP broadcasts and link-local multicast traffic to localized VLANs, preventing broadcast storms from degrading core switch fabrics.

Zero-Trust Boundaries

Isolates sensitive production database clusters from public web tiers using stateless Network ACLs and stateful firewall rules.

Address Conservation

Eliminates address fragmentation by sizing subnets precisely to the host workload capacity required by each microservice.

02 // BIT STRUCTURE

Anatomy of an IPv4 Address: 32-Bit Dual Hierarchy

Every IPv4 address consists of 32 binary bits divided into four 8-bit octets separated by dots. An address is divided into two distinct components: Network Bits (identifying the subnet wire ID) and Host Bits (identifying the specific device interface).

03 // BITWISE ALGEBRA

Bitwise Boolean Mathematics: AND, OR, and NOT Operations

Routers calculate network boundaries using hardware Boolean operations: Network Address = IP AND Subnet Mask, Wildcard Mask = NOT Subnet Mask, and Broadcast Address = Network OR Wildcard Mask.

04 // STANDARDS

RFC 1918 Private IP Address Spaces in Cloud Architecture

The IETF reserved three private address blocks: Class A (10.0.0.0/8), Class B (172.16.0.0/12), and Class C (192.168.0.0/16). These blocks are dropped by internet core BGP routers and require NAT for public internet access.

05 // TUTORIAL

How to Calculate Subnet Mask from IP Address: Step-by-Step

Calculating a subnet mask from an IP address and CIDR prefix length is a core skill for network engineers. Follow this 4-step bitwise methodology:

1. Identify Prefix Length & Network Bits

In CIDR notation (e.g. 192.168.1.50/26), /26 indicates 26 contiguous network 1-bits and 6 host 0-bits (32 - 26 = 6).

2. Convert Binary Octets to Decimal Netmask

Group 32 bits into 4 octets: 11111111.11111111.11111111.11000000. Converting each octet into decimal yields 255.255.255.192.

3. Compute Subnet Block Increment

Subtract interesting octet from 256: 256 - 192 = 64. Subnets increment in blocks of 64: .0, .64, .128, .192. 50 falls in 192.168.1.0.

4. Establish Usable IP Address Ranges

Total capacity is 2^6 = 64. Usable hosts: 64 - 2 = 62. Usable host range: 192.168.1.1 to 192.168.1.62. Broadcast: 192.168.1.63.

06 // VLAN & NETMASK

VLAN Calculator, Subnetting & Network Mask Architecture

A VLAN calculator enables network administrators to design Virtual Local Area Networks (IEEE 802.1Q) mapped 1:1 to distinct IP subnets, containing broadcast traffic and enforcing security perimeters.

Subnet Mask / Netmask

Identifies the routing boundary between network wire ID and assignable host interfaces (e.g. 255.255.255.0 for a /24).

Cisco Wildcard Mask

The bitwise inverse of the netmask used in Cisco IOS ACLs and OSPF network statements (e.g. 0.0.0.255).

IP Address Ranges

The contiguous block between first and last usable host IP assigned via DHCP scopes or static interfaces.

07 // GLOBAL & HERITAGE

Evolution from Classic IP Calculators (Jodies IP Calc, Subnetting Rechner, Calcul IP)

For over three decades, network engineers relied on terminal utilities such as Jodies IP Calculator (ipcalc) by Jochem van der Biezen, as well as classic regional web utilities like the German Subnetting Rechner, French Calcul IP, and Italian Calcolatrice IP. ipvsubnetcalculator.com advances this heritage with instant zero-latency client-side computation and zero-log privacy.

Specialized Subnetting Tools & Deep Dives

6 Dedicated Tools

Need deep architectural calculations for specific cloud environments or routing protocols? Explore our standalone engineering tools:

IPv4 Subnet Calculator →

Dedicated CIDR, mask, and usable host console with Cisco CLI snippets.

IPv6 Subnet Calculator →

128-bit SLAAC prefix lengths, address ranges, and RFC 5952 compression.

CIDR & Subnet Mask Chart →

Searchable /0 to /32 table with wildcard masks and binary bit breakdown.

Cloud VPC CIDR Planner →

AWS, Azure & GCP multi-AZ subnets with cloud reserved IP sizing.

IP Range Calculator →

Calculate start-to-end IP spans and convert ranges into minimal CIDR blocks.

Subnetting Formulas & VLSM →

Step-by-step worked examples, math formulas, and RFC 3021 /31 links.

Engineering Knowledge Base

Frequently Asked Questions & Technical Subnetting FAQ

Essential mathematical answers to common networking questions, prefix boundaries, CIDR conversions, and host allocations.

01How to calculate the subnet mask?

To calculate a subnet mask, determine the number of network bits from the CIDR prefix length (e.g., /24). Convert the consecutive network bits to binary 1s and the host bits to 0s across 4 octets of 8 bits each. For a /24 prefix, this results in 24 ones followed by 8 zeros: 11111111.11111111.11111111.00000000, which in decimal is 255.255.255.0.

02Is 255.255.255.0 the same as /24?

Yes, 255.255.255.0 and /24 represent the exact same subnet mask. Dotted-decimal notation is 255.255.255.0, while /24 is CIDR notation indicating 24 consecutive binary 1-bits. Both allocate 24 bits for the network identifier and 8 bits for hosts (254 usable hosts).

03How to calculate subnet mask from IP address?

To calculate a subnet mask from an IP address with CIDR notation (e.g. 192.168.1.100/26): 1) Look at prefix length (/26). 2) Create a 32-bit mask with 26 ones and 6 zeros: 255.255.255.192. 3) The block size is 256 - 192 = 64. Subnets increment by 64, making 192.168.1.64 the network ID and 192.168.1.65 – 192.168.1.126 the usable IP range.

04What is a VLAN calculator and how to calculate subnets for VLANs?

A VLAN calculator helps network engineers plan Layer 2 Virtual LANs (IEEE 802.1Q) and match each VLAN to an isolated Layer 3 IP subnet. For example, assigning VLAN 10 to 10.0.10.0/24 (management, 254 hosts) and VLAN 20 to 10.0.20.0/23 (workstations, 510 hosts). Use our Subnet Divider tab to slice subnets for VLANs automatically.

05What is the difference between a netmask and a subnet mask?

"Netmask" and "subnet mask" are commonly used interchangeably in modern networking. Historically, "netmask" referred to default classful boundaries (Class A: 255.0.0.0, Class B: 255.255.0.0, Class C: 255.255.255.0), while "subnet mask" refers to classless CIDR boundaries (e.g., /26 or 255.255.255.192) that subdivide a network into smaller subnets.

06What is an IP range calculator and how does it determine CIDR ranges?

An IP range calculator takes an IP address and CIDR prefix (or starting and ending IP addresses) and computes the exact boundary of assignable IP addresses. By performing bitwise AND operations between the IP address and the netmask, it identifies the Network wire ID, the Broadcast IP, and the usable IP address range.

07What is Jodies IP Calculator (ipcalc)?

Jodies IP Calculator (ipcalc) is a classic open-source IP subnetting tool originally created by Jochem "Jodie" van der Biezen in 1999. It became the standard on Linux distributions. ipvsubnetcalculator.com provides the modern web successor to Jodies ipcalc, computing bitwise octets, netmasks, broadcast addresses, and reverse DNS PTR records instantly with zero server latency.

08How does a CIDR subnet calculator work?

A CIDR subnet calculator converts Classless Inter-Domain Routing prefixes (/0 to /32) into dotted-decimal subnet masks, Cisco wildcard masks, and host capacities using bitwise binary mathematics. It calculates network boundaries, broadcast addresses, and total vs. usable host addresses according to the formula 2^(32 - CIDR) - 2.

Documentation & Policy

Platform Architecture & Legal Standards

Explore dedicated technical pages detailing our zero-latency bitwise engine, direct engineering channels, zero-log client privacy guarantee, and usage terms.

NETWORK ENGINEERING KNOWLEDGE BASE

Blog

Deep technical dives, real-world architecture examples, and mathematical foundations for network architects, sysadmins, and cybersecurity professionals.

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MISSION & ARCHITECTURE