Calculate IP ranges from CIDR notation online.
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IP Range Calculator
Calculate IP address ranges from CIDR notation. Get all IP addresses in a subnet, network address, broadcast address, and more.
What is IP Range Calculator?
IP Range Calculator helps with IP Range Calculator Online. Calculate IP address ranges from CIDR notation. Get all IP addresses in a subnet, network address, broadcast address, and more.
TempGBox keeps the workflow simple in your browser, so you can move from input to result quickly without extra software.
How to use IP Range Calculator
- Open IP Range Calculator and enter the text, value, file, or settings you want to work with.
- Review the output and adjust the available options until the result matches your use case.
- Copy, download, or reuse the final result in your workflow, content, app, or support task.
Why use TempGBox IP Range Calculator?
- Calculate IP address ranges from CIDR notation. Get all IP addresses in a subnet, network address, broadcast address, and more
- Useful for IP Range Calculator Online
- Fast browser-based workflow with no signup required
Common uses for IP Range Calculator
IP Range Calculator is useful for IP Range Calculator Online. It fits well into quick checks, repeated office work, development flows, content updates, and everyday browser-based problem solving.
Because the tool is available instantly on TempGBox, you can handle one-off tasks and repeated workflows without installing extra software.
FAQ
Is IP Range Calculator free to use?
Yes. IP Range Calculator on TempGBox is free to use and does not require signup before you start.
What is IP Range Calculator useful for?
IP Range Calculator is especially useful for IP Range Calculator Online.
Understanding IP Range Calculator
CIDR (Classless Inter-Domain Routing) notation replaced the legacy classful addressing system in 1993 (RFC 1519) and uses a prefix length to define the network portion of an address. The notation 10.0.0.0/24 means the first 24 bits are the network prefix and the remaining 8 bits (32 - 24 = 8) identify individual hosts, yielding 2^8 = 256 addresses total, with 254 usable (subtracting the network address and broadcast address). A /16 gives 65,536 addresses, a /20 gives 4,096, and a /32 identifies a single host. Understanding this binary math is fundamental to every network engineering task from VLAN segmentation to cloud VPC design.
Every IP range has a network address (all host bits set to 0) and a broadcast address (all host bits set to 1). The first usable host is network address + 1, and the last usable host is broadcast address - 1. For 192.168.1.0/24, the network address is 192.168.1.0, the broadcast address is 192.168.1.255, and usable hosts range from 192.168.1.1 to 192.168.1.254. This distinction matters for router configuration — assigning the network or broadcast address to a device causes routing failures and ARP conflicts.
IANA (Internet Assigned Numbers Authority) delegates address blocks to five Regional Internet Registries: ARIN (North America), RIPE NCC (Europe/Middle East), APNIC (Asia-Pacific), LACNIC (Latin America), and AFRINIC (Africa). Each RIR further allocates blocks to ISPs and organizations. Private address ranges reserved by RFC 1918 — 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 — are not routable on the public internet and are used for internal networks behind NAT. Additionally, 100.64.0.0/10 (RFC 6598) is reserved for Carrier-Grade NAT, and 169.254.0.0/16 is for link-local addresses assigned when DHCP fails.
Supernetting (CIDR aggregation) combines multiple contiguous smaller networks into a single larger prefix. For example, four /24 networks (10.1.0.0/24 through 10.1.3.0/24) can be aggregated into one /22 (10.1.0.0/22) because they share the first 22 bits. This reduces routing table size — a critical concern for internet backbone routers that carry over 1 million BGP prefixes. The inverse operation, subnetting, splits a large block into smaller ones: a /24 can become two /25s, four /26s, or eight /27s, enabling efficient allocation of addresses to differently sized network segments.
Step-by-Step Guide
- Enter an IP address with its CIDR prefix length (e.g., 10.0.0.0/22) or provide a start and end IP address to have the tool calculate the enclosing CIDR block. Both IPv4 notation styles are accepted.
- Review the calculated results: network address, broadcast address, subnet mask in dotted-decimal (e.g., 255.255.252.0 for /22), wildcard mask (inverse of subnet mask, used in ACLs), total address count, and usable host count.
- Examine the first and last usable host addresses. These are the addresses you can actually assign to devices — the network address and broadcast address are reserved and must not be assigned to hosts or interfaces.
- If you need to subnet further, enter one of the calculated sub-ranges with a longer prefix length. For example, to split a /22 into four equal parts, enter each /24 block within the range to see its individual network and broadcast addresses.
- Use the binary representation display to understand exactly which bits form the network prefix and which are host bits. This visualization makes it clear why certain address boundaries are valid CIDR blocks and others are not.
- For network planning, iterate through different prefix lengths to find the smallest block that accommodates your host count plus growth margin. A /27 supports 30 hosts, a /26 supports 62, and a /25 supports 126 — always account for the two reserved addresses.
- Export or copy the results for documentation. Network diagrams, IP address management (IPAM) spreadsheets, and firewall rule sets all need the exact network boundaries your calculator produces.
Real-World Use Cases
A cloud architect designing a VPC for AWS needs to allocate subnets for three tiers (public, private, database) across three availability zones — nine subnets total. Starting from a /16 VPC, they use the calculator to divide it into /20 blocks per AZ, then further into /24 subnets per tier, documenting the exact CIDR for each subnet in their Terraform configuration.
A network engineer troubleshooting connectivity between two office locations discovers that both sites were assigned overlapping 192.168.1.0/24 ranges. They use the calculator to identify non-overlapping /25 subnets within 192.168.1.0/24 to reassign to each site, or to re-address one site to 192.168.2.0/24.
A security analyst needs to write a firewall rule that blocks a range of suspicious IP addresses from 203.0.113.16 to 203.0.113.31. They use the calculator to confirm this is exactly 203.0.113.16/28, then create a single CIDR-based deny rule instead of 16 individual host rules.
An ISP allocates a /21 to a business customer who needs to sub-assign ranges to ten branch offices. The calculator helps determine that eight /24s and two /25s fit within the /21, and shows the exact start/end addresses for each sub-allocation.
Expert Tips
When planning VPC or VLAN address space, always start with more room than you think you need. Re-addressing an active network is one of the most disruptive operations in infrastructure management. Allocate at least a /20 per major environment (production, staging, development) even if current usage only fills a /24.
For quick mental math: a /24 is 256 addresses, and each step down doubles the count (/23 = 512, /22 = 1024, /21 = 2048). Each step up halves it (/25 = 128, /26 = 64, /27 = 32). Memorize this doubling/halving pattern and you can estimate subnet sizes without a calculator in most conversations.
Use the wildcard mask output directly in Cisco ACLs and OSPF network statements. Getting the wildcard mask wrong is one of the top causes of security misconfigurations — an inverted mask that is too broad exposes hosts that should be protected.
Frequently Asked Questions
Why are two addresses "wasted" in every subnet?
The first address in any subnet is the network address (all host bits zero) used to identify the subnet in routing tables, and the last address is the broadcast address (all host bits one) used to send packets to all hosts on the subnet. Neither can be assigned to a device, so a /24 has 256 total addresses but only 254 usable host addresses.
What is the difference between a subnet mask and a wildcard mask?
A subnet mask has 1s in the network portion and 0s in the host portion (e.g., 255.255.255.0). A wildcard mask is the bitwise inverse: 0s in the network portion and 1s in the host portion (e.g., 0.0.0.255). Subnet masks are used in interface configuration, while wildcard masks are used in Cisco ACLs and OSPF network statements.
What is VLSM and why does it matter?
Variable Length Subnet Masking allows a network to use different prefix lengths for different subnets within the same address block. Without VLSM, all subnets must be the same size, wasting addresses when segment sizes vary. A point-to-point link needs only a /30 (2 usable addresses), while a user VLAN might need a /23 (510 addresses).
How do I determine the right subnet size?
Count the number of devices that will need IP addresses on the segment, add at least 20-50% for growth, then find the smallest CIDR block that accommodates that number. Remember to subtract 2 for network and broadcast addresses. For 100 devices, a /25 (126 usable) is tight; a /24 (254 usable) provides comfortable room for growth.
Can a CIDR block start at any IP address?
No. A CIDR block must align to its prefix boundary — the host bits of the starting address must all be zero. For example, 10.0.0.0/22 is valid (last 10 bits are zero), but 10.0.1.0/22 is not because bit 9 of the host portion is set to 1. The calculator automatically flags misaligned CIDR entries.
Privacy: All IP range calculations are performed locally in your browser using client-side JavaScript. No IP addresses or network configurations you enter are transmitted to any server.