CIDR to IP Range Converter

Convert a CIDR notation IP block to its full IP address range, subnet mask, and host count.

CIDR Notation (one per line)

A CIDR to IP range converter turns CIDR notation such as 192.168.1.0/24 into the actual addresses the block covers. Paste one block per line, and this free tool returns the network address, first and last usable IP, broadcast address, subnet mask and usable host count. It suits network admins, developers and security teams.

What Is CIDR Notation and How Does It Define an IP Range?

CIDR notation writes a block of IPv4 addresses as a starting address, a slash and a prefix length, such as 192.168.1.0/24. The prefix length tells you how many of the 32 bits are fixed as the network portion. The remaining bits identify individual addresses inside the block.

CIDR stands for Classless Inter-Domain Routing. It replaced the older Class A, B and C scheme, which could only split networks at 8, 16 or 24 bits. With CIDR, any prefix from /0 to /32 is valid, so an address block can be sized to fit the network that needs it.

The math is simple. A block holds 2 to the power of (32 minus the prefix) addresses. A /24 holds 2 to the power of 8, which is 256 addresses. A /16 holds 65,536 and a /8 holds 16,777,216. A smaller prefix number always means a bigger block.

Why Convert CIDR to a Range?

Many systems still ask for a start and end address instead of a prefix. Firewall rules, spreadsheets, log filters, geo-IP databases and older admin panels often work that way. Converting by hand means binary math, and one wrong bit gives you the wrong boundary.

How to Use the CIDR to IP Range Converter

You can convert one block or a whole list in a few seconds. Here is the process, using the labels on the page.

Click the CIDR Notation (one per line) box. The placeholder shows the expected format: 192.168.1.0/24, 10.0.0.0/8 and 172.16.0.0/12.
Type or paste your blocks, one per line. Each line needs four dot-separated numbers, a slash and a prefix from 0 to 32.
Click Convert to IP Range.
Read the results table. Each line gets a row with the CIDR you entered, the Network address, the IP Range, the Broadcast address, the Subnet Mask and the Usable Hosts count.
Fix any row that shows an error message, then click the button again. Valid lines still convert even when another line fails.

If you click the button with an empty box, the tool asks you to enter at least one CIDR.

Worked Example: Three Common Blocks

The easiest way to see what the converter returns is to run the three sample blocks from the input box. Here is what the usable range and host count look like for each.

CIDR	Usable IP Range	Usable Hosts
192.168.1.0/24	192.168.1.1 to 192.168.1.254	254
10.0.0.0/8	10.0.0.1 to 10.255.255.254	16,777,214
172.16.0.0/12	172.16.0.1 to 172.31.255.254	1,048,574

For 192.168.1.0/24, the network address is 192.168.1.0, the broadcast address is 192.168.1.255 and the subnet mask is 255.255.255.0. The block has 256 addresses, but two are reserved, so 256 minus 2 leaves 254 usable hosts.

The /12 row shows why people use a converter. The mask is 255.240.0.0, and the range ends at 172.31.255.254, not 172.16.255.254. The boundary falls in the second octet, which is hard to spot without doing the bit math. These three blocks are the private ranges defined in RFC 1918.

How Do You Read and Use the Results?

Each column answers a different question, and knowing which one to copy keeps you from misconfiguring a device.

Network and Broadcast

The Network column is the first address in the block. It identifies the subnet itself and is not assigned to a device. The Broadcast column is the last address, used to reach every host on the subnet. Neither is a usable host address in a standard subnet.

IP Range

The IP Range column shows the first and last usable host addresses, not the network and broadcast addresses. For 192.168.1.0/24 it reads 192.168.1.1 to 192.168.1.254. If a system wants the full span of the block, use the Network value as the start and the Broadcast value as the end.

Subnet Mask and Usable Hosts

The Subnet Mask is the prefix written in dotted form. /24 is 255.255.255.0, and /28 is 255.255.255.240. Usable Hosts tells you whether the block is big enough. If you need 50 devices, a /26 gives 62 usable addresses and fits, while a /27 gives only 30 and does not.

Quick Prefix Reference

/32: 1 address, a single host
/31: 2 addresses, used for point-to-point links
/30: 2 usable hosts
/29: 6 usable hosts
/28: 14 usable hosts
/27: 30 usable hosts
/26: 62 usable hosts
/25: 126 usable hosts
/24: 254 usable hosts
/16: 65,534 usable hosts

What Happens With /31 and /32?

These two prefixes are special cases. A /32 is one address, so the range starts and ends at the same IP, the broadcast shows Not applicable and the host count is 1. A /31 has two addresses and no broadcast, so both are listed as usable, which matches how point-to-point links are commonly configured.

Who Uses a CIDR to IP Range Converter?

Anyone who has to move between prefix notation and plain address ranges will use this regularly. These are the typical situations.

Network engineers check that a planned subnet has enough hosts before configuring a router or VLAN.
Security teams turn a CIDR blocklist or allowlist from a threat feed into start and end addresses for a firewall that does not accept prefixes. After that, an ASN lookup can show who owns an address you want to investigate.
Developers sanity-check the output of their own code. If you build a range calculation with Python's standard ipaddress module, paste the same blocks here and compare the results.
Cloud and hosting admins confirm what a provider's published range covers before opening access to it.
SEO and web teams look at the address blocks behind a hosting setup. The Class C IP checker shows which sites share a /24, and this converter then lays out that block.

If you need a list for a spreadsheet, convert your blocks here and copy the values you need from the table. The page does not offer an export button.

Best Practices, Common Mistakes and Troubleshooting

Most problems come from the input format or from misreading the usable range. These are the cases you are most likely to hit.

What Do the Error Messages Mean?

Invalid CIDR: the line does not contain exactly one slash. An entry like 192.168.1.0 with no prefix, or 192.168.1.0/24/8, triggers it.
Prefix must be a whole number from 0 to 32: the part after the slash is not a one- or two-digit number. Letters, decimals and empty prefixes all fail.
Invalid prefix: the number is outside 0 to 32, for example /33.
Invalid IP: the address is not four numbers from 0 to 255 separated by dots. 192.168.1.256/24 and 192.168.1/24 both fail.

Why Is the Network Different From the Address I Typed?

If you enter 192.168.1.77/24, the Network column shows 192.168.1.0. The converter aligns the address to the block boundary, because the prefix defines which bits belong to the network. The row still shows the CIDR you typed, so you can match it to your source.

Other Tips

Remove ranges written with a hyphen, such as 10.0.0.1-10.0.0.50, before converting. The tool only accepts CIDR notation.
Do not leave a trailing comma or text after the prefix. Put each block on its own line instead.
Do not paste a range in the usable-range format into a firewall that expects the network and broadcast. Check which one your system wants.
When sizing a subnet, plan for growth. A /27 with 30 hosts fills up fast, and renumbering later is painful.
For a single IP's location and owner, use bulk IP lookup or check your own address with My IP Address.

Limitations to Keep in Mind

This converter works with IPv4 only. An IPv6 block such as 2001:db8::/32 returns an Invalid IP message, because IPv6 uses a 128-bit address and a different notation.

It also performs a pure address calculation. It does not tell you who owns a block, whether the addresses are in use, or which domains sit on them. For a full subnet breakdown that includes the wildcard mask, use the subnet CIDR calculator. To see which domains share a server in a block you care about, try a reverse IP lookup. You can find related utilities in the Network and IP tools category.

Paste your CIDR blocks into the box above and click Convert to IP Range. You get the exact network, usable addresses, mask and host count for every line in one table, so you can configure rules and size subnets with confidence.

Frequently Asked Questions

How do I convert CIDR to an IP range?

Paste your CIDR blocks into the CIDR Notation box, one per line, and click Convert to IP Range. The tool returns the network, first and last usable IP, broadcast, subnet mask and usable hosts. For example, 192.168.1.0/24 gives 192.168.1.1 to 192.168.1.254 with 254 hosts.

What is CIDR notation in an IP address?

CIDR notation is an IPv4 address followed by a slash and a prefix length, like 10.0.0.0/8. The prefix says how many of the 32 bits identify the network. A /24 covers 256 addresses and a /8 covers 16,777,216.

Can I convert multiple CIDR blocks at once?

Yes, you can enter as many blocks as you like, one per line, and each gets its own row in the results table. If one line has an error, only that row shows a message and the valid lines still convert.

Why does a /24 show 254 usable hosts instead of 256?

A /24 has 256 addresses, but the first is the network address and the last is the broadcast address, so 254 remain for hosts. The exceptions are /31 and /32, where the tool counts every address as usable.

What does Invalid CIDR or Invalid IP mean?

Invalid CIDR means the line lacks exactly one slash, and Invalid IP means the address is not four numbers from 0 to 255. Check for typos like 192.168.1.256/24 or a missing prefix, correct the line and convert again.

Is this CIDR to IP range tool free, and does it support IPv6?

The tool is free and needs no sign-in. It supports IPv4 only, so an IPv6 block such as 2001:db8::/32 returns an Invalid IP message. Use it for IPv4 blocks with prefixes from /0 to /32.