Subnet Calculator
Free online subnet calculator trusted by 100,000+ network engineers. Calculate IP ranges, CIDR notation, and subnet masks instantly for AWS, Azure, and GCP.
IPv4 Subnet Calculator
Advanced Features
🔍 Compare Two Subnets
Compare two subnets to see if they overlap, contain each other, or are completely separate.
Comparison Results
The subnets are completely separate - they do not share any IP addresses.
🧮 VLSM Calculator (Variable Length Subnet Masking)
Create multiple subnets of different sizes from a single network. VLSM optimizes IP address utilization by allocating exactly the right subnet size for each requirement.
VLSM Benefits:
- • Reduces IP address waste by up to 80%
- • Automatically calculates optimal subnet sizes
- • Perfect for complex network designs
- • Supports up to 100 different subnet requirements
Need to Validate IP Addresses?
Before configuring your subnets, ensure your IP addresses are properly formatted with our comprehensive IP validator. Supports both IPv4 and IPv6 with detailed analysis and error detection.
Validate IP AddressesComplete Subnet Calculator Toolkit
11 free networking tools built for network engineers, cloud architects, and developers. Every tool you need for subnet planning, IP management, and network design — in one place.
Subnet Calculator
Calculate IPv4 subnet ranges, CIDR notation, network and broadcast addresses, usable host counts.
IPv6 Subnet Calculator
Compute IPv6 network prefixes, address ranges, and allocation boundaries for dual-stack planning.
VLSM Calculator
Allocate variable-length subnets from a parent CIDR block to minimize IP address waste.
Supernet Calculator
Aggregate multiple subnets into the smallest covering CIDR for route summarization.
Subnet Overlap Checker
Detect conflicting CIDR ranges before deploying VPC peering, VPNs, or multi-cloud networks.
Wildcard Mask Calculator
Convert between subnet masks, wildcard masks, and CIDR with Cisco ACL examples.
IP Converter
Transform IP addresses between decimal, binary, hexadecimal, integer, and CIDR formats.
Bandwidth Calculator
Convert between Mbps, Gbps, KBps and estimate file transfer times with latency.
IP Validator
Validate and analyze IPv4 and IPv6 addresses with class detection and format checks.
IP Geolocation
Look up the geographic location, ISP, and organization for any IP address.
Routing Simulator
Learn how routers make forwarding decisions with an interactive routing table simulation.
How to Use Our Subnet Calculator
Enter an IP Address
Type any IPv4 address like 192.168.1.0 into the subnet calculator.
Select Subnet Mask
Choose CIDR notation (/24) or decimal (255.255.255.0).
Get Results
Instantly see network address, broadcast, usable range, and host count.
Our subnet calculator is built for network engineers who need accurate results fast. It handles CIDR notation, subnet masks, network and broadcast addresses, usable IP ranges, and host counts — with special support for cloud providers like AWS, Azure, and GCP that reserve additional IPs per subnet.
Whether you're planning a new VPC, studying for the CCNA, or troubleshooting a production network, this subnet calculator gives you everything you need. All calculations run in your browser — your network data stays private.
Frequently Asked Questions
What is a subnet calculator?
A subnet calculator computes IP address ranges, CIDR notation, subnet masks, and network boundaries from an IP address and prefix length. It's essential for network planning, security segmentation, and cloud infrastructure design.
Does this subnet calculator work for AWS VPC planning?
Yes. Our subnet calculator accounts for the 5 reserved IPs per subnet in AWS VPCs (network, router, DNS, future use, broadcast), giving you accurate usable host counts for cloud deployments.
Is this subnet calculator free?
Completely free, no registration required. All 11 networking tools are available at no cost with unlimited usage.
What's the difference between CIDR notation and subnet masks?
They represent the same thing differently. CIDR notation like /24 means 24 network bits. The equivalent subnet mask is 255.255.255.0 (24 ones followed by 8 zeros in binary). Our subnet calculator converts between both formats.