Subnet Calculator
Calculate subnet with our free tool. Get data-driven results, visualizations, and actionable recommendations. Enter your values for instant results.
Formula
Network Address = IP AND Subnet Mask; Broadcast = Network OR Wildcard Mask
The network address is found by performing a bitwise AND between the IP address and subnet mask. The broadcast address is found by performing a bitwise OR between the network address and the wildcard mask (inverse of subnet mask). Usable hosts = 2^(32-CIDR) - 2 (subtracting network and broadcast addresses). The CIDR prefix length indicates how many leading bits form the network portion.
Worked Examples
Example 1: Standard Home Network (/24)
Problem: Calculate subnet details for IP 192.168.1.100 with CIDR /24.
Solution: IP: 192.168.1.100\nCIDR: /24 → Subnet Mask: 255.255.255.0\n\nBinary IP: 11000000.10101000.00000001.01100100\nBinary Mask: 11111111.11111111.11111111.00000000\n\nNetwork (AND): 11000000.10101000.00000001.00000000 = 192.168.1.0\nBroadcast (OR wildcard): 192.168.1.255\nWildcard: 0.0.0.255\n\nUsable range: 192.168.1.1 - 192.168.1.254\nTotal hosts: 256, Usable: 254
Result: Network: 192.168.1.0 | Range: .1-.254 | Broadcast: .255 | 254 usable hosts
Example 2: Enterprise Subnet (/26)
Problem: Subnet 10.0.5.67/26 — find the network, broadcast, and usable range.
Solution: IP: 10.0.5.67\nCIDR: /26 → Subnet Mask: 255.255.255.192\nWildcard: 0.0.0.63\n\n67 in binary: 01000011\nMask last octet: 11000000\nAND: 01000000 = 64\n\nNetwork: 10.0.5.64\nBroadcast: 10.0.5.64 + 63 = 10.0.5.127\nFirst host: 10.0.5.65\nLast host: 10.0.5.126\nUsable hosts: 62
Result: Network: 10.0.5.64 | Range: .65-.126 | Broadcast: .127 | 62 usable hosts
Frequently Asked Questions
How do I determine the right subnet size for my network?
To choose the right subnet size, count the number of devices that need IP addresses and select a CIDR prefix that provides enough usable addresses with room for growth. Include all devices: computers, phones, printers, IoT devices, network equipment, and servers. Plan for 50-100% growth beyond current needs. For 10 devices: /28 gives 14 usable addresses. For 25 devices: /27 gives 30 usable addresses. For 50 devices: /26 gives 62 usable addresses. For 100 devices: /25 gives 126 usable addresses. For 200 devices: /24 gives 254 usable addresses. Remember that every subnet loses 2 addresses (network and broadcast), and you may need addresses for the default gateway, DHCP server, DNS server, and other infrastructure. A common mistake is choosing a subnet that exactly matches current needs — always leave headroom. For VLANs in enterprise networks, /24 is the most common choice for general-purpose subnets.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.
Is Subnet Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.
Does Subnet Calculator work offline?
Once the page is loaded, the calculation logic runs entirely in your browser. If you have already opened the page, most calculators will continue to work even if your internet connection is lost, since no server requests are needed for computation.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.