IP Subnet Calculator | IPv4 & IPv6 - SkyConverterTools

Calculate subnet masks, network addresses, broadcast addresses, and usable host ranges for both IPv4 and IPv6. Supports classful networks and VLSM with an easy dropdown.

IPv4 Subnet Calculator

IP Address
Network Class (optional)
Subnet Mask (CIDR)

IPv4 Address Classes (Classful)

ClassLeading BitsNetwork BitsHost BitsDefault MaskAddress Range
A0824255.0.0.0 (/8)1.0.0.0 – 127.255.255.255
B101616255.255.0.0 (/16)128.0.0.0 – 191.255.255.255
C110248255.255.255.0 (/24)192.0.0.0 – 223.255.255.255
D (Multicast)1110---224.0.0.0 – 239.255.255.255
E (Reserved)1111---240.0.0.0 – 255.255.255.255

IPv6 Subnet Calculator

IPv6 Address
Prefix Length

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About CIDR Notation

About IP Subnetting

CIDR (Classless Inter-Domain Routing) is a method for allocating IP addresses and IP routing. It replaces the previous system based on Class A, B and C networks. Subnetting allows you to divide a large network into smaller, efficient subnets.

Our calculator supports both classful and classless (VLSM) subnetting. Use the dropdown to select any subnet mask from /1 to /32.

How to Use

  1. Enter IP: Type an IPv4 address (e.g., 223.181.33.117).
  2. Select Class (optional): Choose a class to auto-fill typical network addresses.
  3. Pick Subnet Mask: Use the dropdown to select a mask (from /1 to /32).
  4. Calculate: Click "Calculate" to see detailed network details.

Who Should Use This IP Subnet Calculator?

Network Admins

Plan subnets, allocate IP ranges, configure routers.

IT Professionals

Set up office networks, VLANs, troubleshoot.

Developers & DevOps

Design VPCs, subnets in AWS/Azure.

Students

Learn subnetting, prepare for certifications.

Security Experts

Define security zones, analyze perimeters.

Small Business Owners

Understand basic office network setup.

Frequently Asked Questions

IPv4 vs IPv6 subnetting?
IPv4 uses 32-bit addresses, often requires subnetting; IPv6 uses 128-bit and typically /64 subnets. IPv6 has no broadcast addresses.
Usable hosts in a /24?
/24 has 256 total addresses, 254 usable (network and broadcast reserved). For /31 and /32 special rules apply.
What is VLSM?
Variable Length Subnet Mask allows different subnet masks in the same network, optimizing address usage.