How to read the result
Network address is the first address in the block.
Broadcast address is the final address in a conventional subnet.
Wildcard mask is the inverse of the subnet mask and is commonly used in ACL rules.
IPv4 NETWORK CALCULATOR
Calculate CIDR ranges
and subnets in seconds.
Find network boundaries, split a block into equal subnets, and check two IPv4 ranges for overlap before deployment.
01 · CIDR CALCULATOR
Get network boundaries from one address.
A host address is normalized to the start of its network block.
Normalized network
—
Broadcast—
Usable range—
Subnet mask—
Wildcard—
Total addresses—
Usable addresses—
Enter a CIDR to see how the range is calculated.
02 · SUBNET SPLITTER
Split a network into equal-sized blocks.
Choose a target prefix larger than the source prefix. Up to 1,024 rows are shown.
Split result—
| # | CIDR | First usable IP | Last usable IP | Broadcast | Usable |
|---|
Why does /24 split into four /26 blocks?
Increasing the prefix from 24 to 26 adds two network bits, producing 2² or four blocks.
Each /26 contains 64 addresses and normally provides 62 usable host addresses.
03 · CIDR OVERLAP CHECK
Check two address ranges before deployment.
Both values are normalized to their CIDR network boundaries before comparison.
Enter two CIDRs.
The result appears here.
—Why check overlap first?
Overlapping ranges make routing ambiguous across VPC peering, VPNs, and connected private networks.
IPv4 CIDR blocks are either separate, equal, or one contains the other after normalization.
Important calculation rules
Keep these exceptions in mind before applying a result to a network design.
/31 and /32 are special
A /31 can use both addresses on a point-to-point link, while a /32 represents one host. Conventional network and broadcast exclusions do not apply in the same way.
Host addresses are normalized
Entering 192.168.10.35/24 produces 192.168.10.0/24 because calculations use the actual block boundary.
Overlap affects connectivity
Overlapping private ranges can break routing between networks. Confirm the policies of your platform and devices before deployment.
Where this calculator helps
Use the result as a verified input to a network plan, not as a replacement for platform routing policy.
VPC and VPN overlap checks
Compare private ranges before connecting environments so overlapping routes are discovered before deployment.
Equal-size VLAN planning
Split one allocation into consistent child prefixes and verify the first, last, and broadcast addresses.
ACL wildcard calculation
Read the inverse mask beside the subnet mask, then confirm the syntax required by the target device.
Calculation basis
IPv4 addresses are converted to unsigned 32-bit values, masked at the selected prefix, and converted back to dotted decimal.
Overlap is determined from normalized start and end addresses. A /31 exposes both point-to-point addresses and a /32 represents one host.
Checks you can reproduce
These vectors cover normalization, splitting, and containment.
Host normalization
192.168.10.35/24 becomes 192.168.10.0/24 with broadcast 192.168.10.255.
/24 split into /26
Two added prefix bits create four blocks: .0, .64, .128, and .192.
Contained range
10.0.0.0/16 contains 10.0.64.0/18, so the two ranges overlap.
CIDR calculator FAQ
Does the calculator support IPv6?
No. This surface is limited to IPv4 CIDR input.
Does overlap prove two networks can communicate?
No. Route tables, firewalls, NAT, and platform policy still determine connectivity.
Why does a host address change?
The calculator normalizes it to the first address of the selected network block.
Calculation review
Last reviewed · Logic version 20260724-1 · Vectors: /24, /31, /32, split, overlap