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IP Subnet Planner
Zero Upload IPv4 & IPv6Calculate IPv4/IPv6 subnets and ranges.
Prefix length
/24 ยท 8 host bits
Specify a prefix if your input omits it.
Invalid CIDR block.
Quick host fit
Ready when you need it.
Validation
- Enter a CIDR block to begin.
Network ID
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Prefix โ
Address range
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First ยท Last
Capacity
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Usable hosts
Classification
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Notes
Detailed breakdown
IPv4Binary & Hex
Expanded
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Bit pattern
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Neighboring Prefixes
| Prefix | Mask / hosts | Notes |
|---|
Subnet Explorer
Split the analyzed block into smaller CIDRs.
This block cannot be subdivided further.
| CIDR | Range | Usable hosts |
|---|
Select a prefix to preview subnets.
IP Address Formats
View the network address in multiple formats.
Decimal Dotted
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Binary
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Hexadecimal
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Integer (Decimal)
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IPv4-mapped IPv6
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IPv6 Expanded
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IPv6 Compressed
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Reverse DNS (PTR)
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What is CIDR?
Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and IP routing. It replaced the older system based on classes (A, B, and C) to provide more flexibility and efficiency in address distribution.
How to Use This Tool
Enter an IP address with a prefix (e.g., 192.168.1.0/24) or use the slider to adjust the prefix length. Click "Run analysis" to see network details, usable host ranges, and binary representations.
Common Use Cases
Planning network subnets for cloud infrastructure (VPCs), troubleshooting routing issues, calculating host capacity for a given prefix, and converting between CIDR and subnet masks.
Pro Tips
Remember that in IPv4, the first and last addresses in a subnet are typically reserved for the network ID and broadcast address. In IPv6, subnets are almost always /64 for standard local networks.
Common Subnets
| CIDR | Subnet Mask | Hosts | Use Case |
|---|---|---|---|
/32 | 255.255.255.255 | 1 | Single host |
/24 | 255.255.255.0 | 254 | Small network |
/16 | 255.255.0.0 | 65,534 | Medium network |
/8 | 255.0.0.0 | 16M+ | Large network |
Private Ranges (RFC 1918)
| Range | CIDR | Class |
|---|---|---|
| 10.0.0.0 โ 10.255.255.255 | 10.0.0.0/8 | A |
| 172.16.0.0 โ 172.31.255.255 | 172.16.0.0/12 | B |
| 192.168.0.0 โ 192.168.255.255 | 192.168.0.0/16 | C |
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