IPv4 Subnet Calculator – Network and Host Addresses
Calculate subnet network address, broadcast, and usable hosts from IP and CIDR.
About This Calculator
Calculate subnet network address, broadcast, and usable hosts from IP and CIDR. Use the calculator above for instant results.
Worked Examples
Example 1: 192.168.1.100/24
- Network: 192.168.1.0 | Mask: 255.255.255.0
- Broadcast: 192.168.1.255 | Usable: 254 hosts
Answer: 192.168.1.0/24
Example 2: 10.0.0.0/8
- Usable hosts: 16,777,214 (Class A range)
Answer: 10.0.0.0/8
Example 3: 172.16.5.50/28
- Network: 172.16.5.48 | 14 usable hosts
Answer: 172.16.5.48/28
Who Uses This Calculator?
Network Engineers
Subnetting and IP planning.
IT Admins
Verify network configurations.
CCNA Students
Subnetting exam practice.
CS Teachers
Networking curriculum.
Common Mistakes to Avoid
❌ CIDR vs subnet mask
CIDR /24 = subnet mask 255.255.255.0. Both are equivalent notations.
❌ Usable hosts = total - 2
Subtract 2 for network address and broadcast. /24 has 256 addresses but 254 usable.
Frequently Asked Questions
Common subnet sizes?
/24: 254 hosts. /25: 126. /26: 62. /27: 30. /28: 14. /29: 6. /30: 2 (point-to-point).
Private IP ranges?
10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16. Non-routable on public internet.
Subnetting shortcut?
Each prefix +1 halves hosts: /24=254, /25=126, /26=62, /27=30...