Subnet Calculator
Free online subnet calculator for network engineers and developers. Calculate IP ranges, CIDR notation, and subnet masks instantly — with accurate reserved-IP handling for AWS, Azure, and GCP.
IPv4 Subnet Calculator
Results
Network Map
Summary
Binary Representation
IP addresses are stored as binary numbers (1s and 0s) in computers. This is how your network looks in binary:
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.
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
25+ 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 a single input like an IP address and prefix length. Given 192.168.1.0/24, for example, it instantly returns the network address (192.168.1.0), broadcast address (192.168.1.255), usable host range (192.168.1.1–192.168.1.254), subnet mask (255.255.255.0), and total host count (254 usable addresses out of 256). This replaces manual binary math — converting the prefix length into a mask, ANDing it against the IP address, and working out the broadcast address by hand — which is slow and error-prone at scale. Subnet calculators are essential for network planning, security segmentation, and cloud infrastructure design in AWS, Azure, and GCP, where VPC and VNet subnet sizing directly affects how many hosts, load balancers, and reserved IPs a subnet can support.
Does this subnet calculator work for AWS VPC planning?
Yes. AWS reserves 5 IP addresses in every VPC subnet: the network address, the VPC router address, two addresses reserved for DNS, and the broadcast address (even though VPCs don't support broadcast traffic). A standard /24 subnet, which normally has 254 usable addresses, only yields 251 usable host addresses inside a VPC. Our subnet calculator accounts for this automatically — switch to AWS mode and it recalculates the usable host count, first usable IP, and last usable IP using AWS's actual reservation rules instead of generic textbook CIDR math. This matters most when sizing subnets for EC2 instance pools, EKS worker nodes, or RDS subnet groups. The same AWS-aware logic is available standalone on the AWS Subnet Calculator page, and Azure and GCP each have their own dedicated reserved-IP calculators.
Is this subnet calculator free?
Completely free, with no registration, no paywall, and no usage limits. All 25+ networking tools on this site — including the CIDR calculator, VLSM calculator, IPv6 subnet calculator, subnet overlap checker, and Kubernetes IP planning tools — are available at no cost and run entirely in your browser. Calculations happen client-side in JavaScript, so no IP addresses, CIDR ranges, or network data are ever sent to a server or logged; this also means the tools keep working offline once the page has loaded. There are no ads embedded in the calculators, no email gate blocking results, and no tracking scripts monitoring what you calculate.
What's the difference between CIDR notation and subnet masks?
CIDR (Classless Inter-Domain Routing) notation combines an IP address with a slash and a number, like 192.168.1.0/24, where the number specifies how many leading bits of the address are fixed as the network portion. /24 means 24 network bits and 8 host bits, equivalent to a subnet mask of 255.255.255.0; /16 means 16 network bits (255.255.0.0), and /30 means 30 network bits, leaving only 2 host bits for point-to-point links. Enter any CIDR block into the calculator above and it converts between CIDR prefix and dotted-decimal subnet mask, then derives the network address, broadcast address, usable IP range, wildcard mask, and host counts in real time as you type.