Subnet & CIDR Visualizer
Compute IPv4 and IPv6 CIDR details — network address, range, mask, usable host count, binary view, and a two-CIDR overlap comparison. Pure BigInt math, supports every prefix from /0 to /128.
Samples:
How to use
- 1 Enter an IPv4 or IPv6 CIDR like 192.168.1.0/24 or 2001:db8::/32.
- 2 Review the network address, broadcast, mask, usable hosts, and binary visualization.
- 3 Optionally enter a second CIDR to check overlap and inclusion.
Related tools
Blood Type Calculator
Use Blood Type Calculator online for free. Your files and data stay in your browser.
Date/Time Calculator
Use Date/Time Calculator online for free. Your files and data stay in your browser.
Income Tax Calculator
Use Income Tax Calculator online for free. Your files and data stay in your browser.
Loan Calculator
Use Loan Calculator online for free. Your files and data stay in your browser.
Relative Title Calculator
Use Relative Title Calculator online for free. Your files and data stay in your browser.
What to Eat
Use What to Eat online for free. Your files and data stay in your browser.
About this tool
This CIDR calculator is built for network engineers, SREs, cloud architects, and anyone learning networking. Drop in an IPv4 or IPv6 CIDR and get back the network address, broadcast, mask, first/last usable host, usable host count, binary representation, and an address-range bar. All math runs on the browser's native BigInt — no server, no leaks, no API.
New in v2: full IPv6 support. Parse both compressed (2001:db8::/32) and full (2001:0db8:0000:...) formats, output both shortest and full text representations, and support every prefix from /0 to /128. New: dual-CIDR overlap comparison — enter two CIDRs to see whether they intersect, which one contains the other, and where they sit on the address bar.
Designed for AWS / Azure / GCP VPC planning, firewall rule authoring, Kubernetes Pod CIDR allocation, routing conflict debugging, and IPv6 training.
Frequently asked questions
How many usable IPs are in /24, /16, or /8? +
/24 has 256 IPs (254 usable), /16 has 65,536 IPs (65,534 usable), /8 has 16,777,216 IPs. Each step down in prefix length doubles the size; each step up halves it. /31 (RFC 3021 point-to-point) has 2 usable, /32 is a single host. IPv6 always uses every address (no broadcast), so /64 has 2^64 addresses.
How is IPv6 CIDR calculation different from IPv4? +
The math is identical — just 128 bits instead of 32. /64 is the standard subnet boundary in IPv6 (64 bits network + 64 bits interface ID), /48 is the typical prefix an ISP assigns to an enterprise, /128 is a single host. IPv6 has no broadcast address, so every address is usable.
How does the dual-CIDR overlap check work? +
The tool computes the address range for each CIDR and tells you whether they intersect, and whether one fully contains the other. This is invaluable when debugging 'why can't these two VPC subnets coexist' or 'why is this route shadowing that one' questions.
Does the tool support private IP ranges? +
Yes. RFC 1918 private ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), IPv6 unique local addresses (fc00::/7), loopback, and link-local are all handled. The calculator treats public and private space identically.
What is the binary visualization? +
The tool renders the subnet mask as a 32-bit (IPv4) or 128-bit (IPv6) strip of colored squares — one color for network bits (1s) and another for host bits (0s). This makes the prefix boundary visible at a glance, which is far easier than parsing a dotted-decimal or hex mask.