v2.0 · cloud-native

The modern subnet toolkit built for cloud & network engineers.

Every CIDR calculation, VLSM plan, and cloud-aware subnet you need — with binary visualization, Terraform export, and a built-in learning center. No signup. Free forever.

Open Calculator → Learn Subnetting

Tools

~4ms

Calc time

AWS·GCP·K8s

Cloud-aware

100%

Free forever

~/calculator · ipv4 AWS VPC

IP Address

CIDR

◆IPv4 calculator ◆IPv6 subnetting ◆VLSM planner ◆Supernet aggregation ◆AWS VPC reserved IPs ◆Kubernetes Pod CIDR ◆Terraform export ◆Cisco ACL export ◆Overlap detection ◆Learn Center ◆IPv4 calculator ◆IPv6 subnetting ◆VLSM planner ◆Supernet aggregation ◆AWS VPC reserved IPs ◆Kubernetes Pod CIDR ◆Terraform export ◆Cisco ACL export ◆Overlap detection ◆Learn Center

01 / TOOLKIT

Every networking tool, one place.

15 tools · ~4ms calculation · 0 ads

IPv4 / IPv6 Calculator

Network, broadcast, usable range, binary breakdown, wildcard mask — with copy buttons on every field.

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VLSM Planner

Variable-length subnetting from a parent CIDR. Up to 100 subnets, minimum-waste allocation.

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Cloud-aware Calculator

AWS, Azure, GCP, OCI, Kubernetes — accounts for provider-reserved IPs automatically.

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EXPORT

IaC Export

Terraform, CloudFormation, Bicep, Pulumi, Ansible, Cisco IOS, Kubernetes YAML.

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AI Subnet Assistant

Describe your network in plain English. Get a VLSM plan, diagram, and exportable config.

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Supernet / Aggregation

Aggregate multiple subnets into the smallest covering CIDR for BGP route summarization.

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Overlap Checker

Detect conflicting CIDR ranges before deploying VPC peering, VPNs, or multi-cloud networks.

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Wildcard Mask Converter

Subnet mask ↔ wildcard mask ↔ CIDR. With Cisco ACL examples ready to copy.

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Reverse Subnetting

Enter how many hosts you need → get the right prefix. Maps to how engineers think.

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NEW

Bandwidth Calculator

Mbps↔MB/s converter, transfer time estimator, Bandwidth-Delay Product for TCP window sizing.

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NEW

Routing Simulator

Build a routing table, pick a destination, watch longest-prefix-match pick the winning route.

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LEARN

Learn Center

Step-by-step lessons, interactive quiz, /0–/32 reference, glossary, and a downloadable cheat sheet PDF.

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PRACTICE

Subnetting Quiz

Random subnet challenges with explanations. Track your streak. Perfect for CCNA / Net+ prep.

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BLOG

Guides & Articles

In-depth guides on VLSM, AWS VPC design, Kubernetes networking, and more.

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02 / LEARN

From zero to subnetting wizard — for free.

109 lessons · interactive quiz · printable PDF

Step-by-step lessons

109 micro-lessons covering CIDR, VLSM, IPv6, cloud, and Kubernetes networking — short, focused, no fluff.

Start learning →

Interactive quiz

Random subnet challenges with full explanations. Tracks your streak in your browser.

Try the quiz →

Full /0–/32 reference

Every prefix length with its mask, wildcard, total addresses, and usable hosts — sortable.

Open reference →

Printable cheat sheet

A one-page PDF you can pin to the wall during exams or use on the job. Free download.

Download PDF →

03 / COMPARISON

How we compare to the rest.

Audited May 2026

Feature	subnetmaskcalc.net	calculator.net	subnetcalculator.dev	TunnelsUp	SolarWinds
Cloud-aware (AWS/Azure/GCP)	●	○	●	○	○
Kubernetes CIDR planner	●	○	○	○	○
Terraform / Cisco config export	●	○	○	○	●
AI subnet designer	●	○	○	○	○
Built-in Learn Center	●	○	○	○	○
Binary visualization	●	○	○	●	○
Shareable URL links	●	○	○	●	○
No signup required	●	○	●	●	○
Modern UI / dark mode	●	○	●	○	○

Ready when you are

Built by engineers, free for engineers.

Open the calculator and start planning. No signup, no email, no upsells. Just the tool you came for.

Open Calculator → Learn Subnetting

Also on the site: the bandwidth calculator (Mbps ↔ MB/s, transfer time, BDP) and the routing table simulator for testing longest-prefix-match behaviour.

FAQ

Frequently asked questions

What is a subnet mask calculator?

A subnet mask calculator takes an IP address and a CIDR prefix (or subnet mask) and returns the network address, broadcast, first and last usable hosts, host count, and wildcard mask. subnetmaskcalc.net adds binary visualization, AWS / Azure / GCP / OCI reserved-IP awareness, VLSM planning, and Terraform / Cisco export — all running in your browser.

Is this subnet calculator free?

Yes, every tool on subnetmaskcalc.net is free with no signup. The site is funded by banner ads and Google Analytics. Your calculator inputs (IPs, CIDRs, network designs) never leave your browser — calculations run client-side in JavaScript.

Does it support IPv6 subnetting?

Yes. The calculator handles both IPv4 and IPv6, with IPv6-specific features like /64 SLAAC compatibility checks, full-form expansion, and prefix arithmetic. See the IPv6 crash course in our blog for a refresher.

Does it account for cloud reserved IPs?

Yes. Switch the calculator to AWS, Azure, GCP, or OCI mode and it applies that provider's reserved-IP math automatically — AWS and Azure reserve 5 IPs per subnet, GCP reserves 4, OCI reserves 3. A /28 in AWS gives 11 usable hosts, not the textbook 14.

Can I export subnet plans to Terraform?

Yes. The IaC Export tool converts subnet plans into Terraform, CloudFormation, Pulumi, Cisco IOS, and JunOS configurations. Plan visually, then copy the generated config into your repository.