Calculate IPv4 CIDR ranges, subnet sizes, wildcard masks, and usable host boundaries with a fast subnetting workflow.
Enter an IPv4 address and a CIDR prefix to calculate subnet boundaries, mask values, and usable host range.
Network boundaries, mask values, host counts, and binary subnet breakdown.
The IPv4 address 203.0.113.9 belongs to the 203.0.113.8/30 network, and the subnet broadcast boundary is 203.0.113.11.
This subnet provides 4 total addresses and 2 usable host addresses, with a host range from 203.0.113.9 to 203.0.113.10.
The subnet mask is 255.255.255.252, the wildcard mask is 0.0.0.3, and the address falls into Class C.
Inspect the binary representation of the IP, subnet mask, network, and broadcast values.
11001011.00000000.01110001.00001001
11111111.11111111.11111111.11111100
11001011.00000000.01110001.00001000
11001011.00000000.01110001.00001011
Useful reminders for subnetting and host calculations.
/24 means 24 network bits and 8 host bits.
Subnet mask shows the network boundary, while wildcard mask is its inverse.
/31 is commonly used for point-to-point links, while /32 represents a single-host route.
Common IPv4 subnet sizes for fast comparison without recalculating each time.
| Prefix | Subnet mask | Total addresses | Usable hosts |
|---|---|---|---|
| /16 | 255.255.0.0 | 65,536 | 65,534 |
| /17 | 255.255.128.0 | 32,768 | 32,766 |
| /18 | 255.255.192.0 | 16,384 | 16,382 |
| /19 | 255.255.224.0 | 8,192 | 8,190 |
| /20 | 255.255.240.0 | 4,096 | 4,094 |
| /21 | 255.255.248.0 | 2,048 | 2,046 |
| /22 | 255.255.252.0 | 1,024 | 1,022 |
| /23 | 255.255.254.0 | 512 | 510 |
| /24 | 255.255.255.0 | 256 | 254 |
| /25 | 255.255.255.128 | 128 | 126 |
| /26 | 255.255.255.192 | 64 | 62 |
| /27 | 255.255.255.224 | 32 | 30 |
| /28 | 255.255.255.240 | 16 | 14 |
| /29 | 255.255.255.248 | 8 | 6 |
| /30 | 255.255.255.252 | 4 | 2 |
| /31 | 255.255.255.254 | 2 | 2 |
| /32 | 255.255.255.255 | 1 | 1 |