Free calculators to help you work with IP addresses, subnets, CIDR notation, and network ranges
Figure out subnet masks, find network addresses, see how many hosts you can fit, and convert everything to binary if you need to.
Work with IPv6 addresses, calculate prefix lengths, see address ranges, and switch between short and long notation formats.
Convert CIDR notation (like /24) to subnet masks and back, figure out what IPs are in a range, and see your network boundaries.
Find all the IPs between two addresses, count how many you've got, see if one range fits inside another, and turn ranges into CIDR blocks.
Calculate wildcard masks for access control lists, match specific IP patterns, and create firewall rules without the headache.
Check DNS propagation across 20+ global servers. Verify A, MX, CNAME, TXT records and monitor DNS changes worldwide in real-time.
Common subnet masks and CIDR notations
Instant results as you type with no delays or loading times
No data stored or sent to servers. Everything runs locally in your browser
Works perfectly on desktop, tablet, and mobile devices
Export results to CSV or JSON for easy documentation
A subnet calculator is basically a tool that helps you figure out how to break up a network into smaller pieces. Think of it like dividing a big apartment building into individual units - you need to know how many units you can fit, what addresses they'll have, and how to keep them organized.
When you're working with IP addresses, especially IPv4 addresses, you've got a limited number of them to work with. A subnet calculator takes an IP address and a subnet mask (or CIDR notation like /24) and tells you things like the network address, broadcast address, how many usable host addresses you get, and what the IP range looks like. It's super handy because doing this math by hand is tedious and you'll probably make mistakes.
Our subnet calculator handles the older IPv4 format and the newer IPv6 addresses. For IPv4, it converts between different formats - like showing you the subnet mask in dotted decimal (255.255.255.0), CIDR notation (/24), or even in binary if you're into that kind of thing. It also does wildcard masks, which are useful for access control lists and routing configurations.
Whether you're planning a new network, troubleshooting connectivity issues, or just trying to understand how subnetting works, a good subnet calculator saves you time and helps prevent configuration errors that could bring down your network.
First, pick which calculator you need. If you're working with regular IP addresses like 192.168.1.1, use the IPv4 subnet calculator. For newer IPv6 addresses with colons, grab the IPv6 calculator. Need to work with CIDR notation? We've got a dedicated CIDR calculator for that. There's also a range calculator if you want to see all the IPs in a subnet, and a wildcard mask calculator for ACL configurations.
Type in the IP address you're working with. For example, if you enter 192.168.1.0, the calculator will use that as your starting point. You can also specify the subnet mask either as a dotted decimal (like 255.255.255.0) or using CIDR notation (like /24). The tool accepts both formats, so use whichever one you're more comfortable with.
Once you enter the information, the calculator shows you everything you need right away. You'll see the network address, broadcast address, the range of usable IP addresses, how many hosts you can fit in that subnet, and the subnet mask in different formats. Some calculators also show you the binary representation, which can be helpful for understanding how subnetting actually works under the hood.
Instead of manually calculating subnet masks and network ranges, you get instant results. What used to take minutes now happens in seconds, letting you focus on actually configuring your network instead of doing math.
Manual calculations are prone to mistakes, especially when you're dealing with binary conversions or large subnet ranges. Our calculators do the math correctly every time, so you don't accidentally create overlapping subnets or misconfigure routing tables.
Need CIDR notation? Binary? Dotted decimal? Our tools convert between all the common formats automatically. This is super useful when you're working with different systems that expect different notation styles.
No downloads, no registration, no credit card required. Just open the calculator in your browser and start using it. Works on any device with internet access, so you can calculate subnets from your phone if you need to.
Our calculators handle both traditional IPv4 addresses and modern IPv6 addresses. Whether you're working with 192.168.1.1 or 2001:0db8:85a3::8a2e:0370:7334, we've got you covered.
Easily convert between CIDR notation (like /24) and subnet masks (like 255.255.255.0). The calculator shows you both formats so you can use whichever one your system requires.
Automatically calculate subnet masks for any IP address and prefix length. See the mask in dotted decimal format, CIDR notation, and binary representation.
Calculate wildcard masks for access control lists and routing configurations. Perfect for network administrators who need to configure ACLs on routers and firewalls.
See the complete range of IP addresses in a subnet, from the network address to the broadcast address. Shows you exactly which IPs are available for use.
Convert IP addresses and subnet masks to binary format. This is helpful for understanding how subnetting works at the bit level and for educational purposes.
When you're setting up a new network or expanding an existing one, subnet calculators help you figure out how to divide your IP address space efficiently. You can plan out your subnets ahead of time, making sure you have enough addresses for each department or location without wasting IPs.
If you're configuring VLANs on a switch, each VLAN typically needs its own subnet. A subnet calculator helps you determine the right subnet size for each VLAN based on how many devices you expect to connect. This prevents you from running out of IPs or wasting address space.
Cloud providers like AWS and Azure use CIDR notation for their VPCs and subnets. Our CIDR calculator makes it easy to work with these blocks, calculate available IP ranges, and ensure your subnets don't overlap when you're setting up multiple VPCs or regions.
When something's not working on your network, a subnet calculator can help you verify that IP addresses are configured correctly. You can check if an IP falls within the expected subnet range, verify subnet masks match what they should be, and identify potential configuration errors.
If you're studying networking or preparing for certifications like CCNA, subnet calculators are great learning tools. They show you the binary math behind subnetting, help you understand how CIDR notation works, and let you experiment with different subnet sizes to see how they affect available host addresses.