Subnet Calculator
CIDR ranges, masks and hosts at a glance.
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- Network (CIDR)
- 192.168.1.0/24
- Network address
- 192.168.1.0
- Broadcast address
- 192.168.1.255
- Subnet mask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- Usable host range
- 192.168.1.1 – 192.168.1.254
- Usable hosts
- 254
- Total addresses
- 256
- Address type
- Private (RFC 1918)
Binary
Split into smaller subnets
4 subnets with 64 addresses each
| Subnet | Usable hosts | Broadcast |
|---|---|---|
| 192.168.1.0/26 | 192.168.1.1 – 192.168.1.62 | 192.168.1.63 |
| 192.168.1.64/26 | 192.168.1.65 – 192.168.1.126 | 192.168.1.127 |
| 192.168.1.128/26 | 192.168.1.129 – 192.168.1.190 | 192.168.1.191 |
| 192.168.1.192/26 | 192.168.1.193 – 192.168.1.254 | 192.168.1.255 |
Examples
The address bar updates as you go, so you can bookmark or share the result.
How to use it
Type an IPv4 address with a prefix (10.0.5.20/22), with a mask (10.0.5.20 255.255.252.0), or pick the prefix from the list. You get every value you need for configs and firewall rules, plus a table that splits the network into smaller subnets.
How CIDR works
An IPv4 address is 32 bits. The prefix — the number after the slash — says how many of those bits identify the network; the rest identify hosts inside it.
- A
/24keeps 24 network bits and leaves 8 for hosts: 2⁸ = 256 addresses. - Two of them are reserved: the network address (all host bits 0) and the broadcast address (all host bits 1).
- So a
/24has 254 usable hosts. In general: usable = 2^(32 − prefix) − 2.
Quick reference
| Prefix | Mask | Addresses | Usable hosts |
|---|---|---|---|
/30 |
255.255.255.252 | 4 | 2 |
/29 |
255.255.255.248 | 8 | 6 |
/28 |
255.255.255.240 | 16 | 14 |
/27 |
255.255.255.224 | 32 | 30 |
/26 |
255.255.255.192 | 64 | 62 |
/24 |
255.255.255.0 | 256 | 254 |
/22 |
255.255.252.0 | 1,024 | 1,022 |
/16 |
255.255.0.0 | 65,536 | 65,534 |
/31 and /32 are special: a /31 is used for point-to-point links where both addresses are usable (RFC 3021), and a /32 is a single host — common in firewall rules and routes.
Private address ranges
| Range | CIDR | Notes |
|---|---|---|
| 10.0.0.0 – 10.255.255.255 | 10.0.0.0/8 |
large networks, cloud VPCs |
| 172.16.0.0 – 172.31.255.255 | 172.16.0.0/12 |
Docker’s default bridge lives here |
| 192.168.0.0 – 192.168.255.255 | 192.168.0.0/16 |
home and small office networks |
| 100.64.0.0 – 100.127.255.255 | 100.64.0.0/10 |
carrier-grade NAT, some VPNs |
Tip
Planning a cloud network? Leave room to grow. A /16 VPC split into /20 or /22 subnets per zone is much easier to live with than a /24 that’s full on day one.
FAQ
What is a wildcard mask?
The inverse of the subnet mask — host bits set to 1. Cisco ACLs and OSPF use it: the mask 255.255.255.0 becomes the wildcard 0.0.0.255.
Why do my two subnets overlap?
Two networks overlap when one’s range contains the other’s network address. For example, 10.0.0.0/16 contains 10.0.4.0/24. Use the split table to carve non-overlapping subnets from one block.
Does this calculator support IPv6?
Not yet — IPv6 support is planned.