Subnet calculator (CIDR)
From CIDR (e.g. 192.168.1.0/24): network, broadcast, mask, hosts. IPv4 and IPv6.
Network with prefix length, for example 192.168.1.0/24 for IPv4 or 2001:db8::/32 for IPv6. Calculated only in your browser.
- Network
- 192.168.1.0/24
- Broadcast
- 192.168.1.255
- Netmask
- 255.255.255.0
- Mask binary
- 11111111.11111111.11111111.00000000
- First host
- 192.168.1.1
- Last host
- 192.168.1.254
- Total addresses
- 256
- Usable hosts
- 254
How this tool works
The subnet calculator computes all important properties from a CIDR notation (e.g. 192.168.1.0/24 or 2001:db8::/32): network address, broadcast address, netmask, number of usable hosts, first and last usable address, plus binary representation. Both IPv4 and IPv6 are fully supported. Plan subnets for VLANs, VPNs or cloud VPCs without playing online-calculator-lottery and skip the mental bit-shifting.
Typical use cases
- Plan a VLAN range on a switch — how many hosts fit in /27?
- Size cloud VPC subnets (AWS VPC, Hetzner Cloud, Azure VNet)
- For OpenVPN/WireGuard setup, check tunnel subnet for conflicts with the LAN
- Compute IPv6 prefixes (/64 for one subnet, /48 for a site)
- During network migrations, determine address space for a new subnet
Frequently asked questions
How many hosts does a /24 net have?
256 total, 254 usable (one is network, one broadcast). At /30 it is 4 addresses / 2 hosts, at /16 it is 65,536 addresses / 65,534 hosts.
What is different in IPv6?
No broadcast — every address is usable. Default subnet is /64 which gives 18 quintillion addresses per net. Site allocations are /48 or /56.
Why does /31 only have 2 addresses?
/31 (RFC 3021) is for point-to-point links only — both addresses are usable, no network/broadcast. Useful for router links, saves IPs.
Which private range for my home network?
192.168.0.0/16 for small nets, 10.0.0.0/8 for larger ones. Avoid 192.168.0.0/24 and 192.168.1.0/24 if you use VPN — too common in hotels/cafés.
Does input also work with netmask instead of CIDR?
Yes — the calculator understands "192.168.1.0/255.255.255.0" and auto-converts.
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