Free IPv4 & IPv6 Subnet Calculator
Design and split networks locally at no cost. Paid plans add secure cloud projects, version history, and team collaboration.
Designs on this page are stored in your browser and can be lost if you clear your data.
Free calculator vs. paid cloud planning
The calculator on this page is free and works without an account. Paid plans add secure cloud projects on top of it.
| Capability | Free | Individual | Teams |
|---|---|---|---|
| IPv4 & IPv6 designer | ✓ | ✓ | ✓ |
| Browser-local design persistence | ✓ | ✓ | ✓ |
| Cloud projects | — | ✓ | ✓ |
| Version history | — | ✓ | ✓ |
| Cross-device access | — | ✓ | ✓ |
| Team collaboration | — | — | ✓ |
How to use the subnet calculator
Enter an IPv4 or IPv6 address with a CIDR prefix, such as 192.168.1.0/24. The prefix length determines the size of the address block: a larger prefix creates a smaller subnet.
- CIDR and network range
- CIDR combines the network address and prefix length. The network range shows the first and last addresses contained in that block.
- Network, broadcast, and usable hosts
- For most IPv4 subnets, the network address is the first address and the broadcast address is the last, so neither is counted as a usable host. IPv4 /31 and /32 are handled separately. IPv6 has no broadcast address.
- Split and label address space
- Split a parent network into smaller subnets, then label each block by site, environment, service, or customer to make the allocation plan easier to review.
How network teams use Subnet Calc
- Plan address space before allocating it. Split a parent prefix into subnets for environments, sites, or customers and see exactly how much space each one consumes.
- Design cloud networks. Lay out VNet and VPC address plans, name each subnet, and export the result for documentation or deployment.
- Pick up where you left off. Paid cloud projects keep your designs and their version history available from any device.
- Work from one shared plan. Team plans give every member the same projects and history, so the address plan has a single source of truth.
What a paid cloud project adds
- Cloud projects. Save playground designs to your account instead of relying on browser storage.
- Version history. Every saved change is kept, so you can review how a design evolved.
- Cross-device access. Open the same projects from any browser once you sign in.
- Project hierarchy. Organize projects with parent and child relationships that mirror your network structure.
- Exports. Export project data with reusable export templates.
- Team collaboration. Share projects across your team — available on team plans only.
Frequently asked questions
Where are my playground designs stored?
Designs you create on this page are stored in your browser's local storage on this device. Clearing your browser data removes them. A paid plan lets you save designs as cloud projects with version history and access from any device.
Do I need to pay to save designs to the cloud?
Yes. Cloud projects require a paid plan. Creating an account on its own does not include cloud projects — the free tier covers the local calculator with browser-local storage.
Does Subnet Calc support IPv6 as well as IPv4?
Yes. The calculator designs and splits both IPv4 and IPv6 networks, and it is free to use without an account.
How does the Individual Lifetime offer work?
Individual Lifetime is a single one-time payment for one user, available while founding member spots remain. The pricing page shows the current price and live availability. Once all spots are claimed, only the annual plan is available.
How many people can share a team plan?
Each team plan has its own member and project limits — see the pricing page for the current limits. Team plans add collaboration; the Individual plan is single-user.