IPv4 & IPv6 Subnet Calculator
Calculate CIDR networks, masks, exact address counts and IPv4 host ranges. Check membership and preview child subnets for IPv4 or IPv6 without scanning any network.
Settings
Try the example or enter your own settings.
This is an address calculator, not a network scanner. Counts do not establish routability, available leases or valid deployment choices. IPv4 /31 uses point-to-point semantics. IPv6 preview includes all mathematical addresses; reserved addresses still need operational review.
Using IPv4 & IPv6 Subnet Calculator
Calculate CIDR networks, masks, exact address counts and IPv4 host ranges. Check membership and preview child subnets for IPv4 or IPv6 without scanning any network.
- Enter an IPv4 or IPv6 address with its CIDR prefix, or try the editable example.
- Optionally check another address or choose a child prefix to divide the network. Clear the child field for only the main summary.
- Calculate, review the JSON and preview, then copy or export. At most 64 child subnets are displayed; counts remain exact.
Example
Try the included editable example. Optionally check another address or choose a child prefix to divide the network. Clear the child field for only the main summary.
Questions & answers
Does it support IPv6?
Yes. It accepts full and compressed IPv6 notation, including an IPv4 tail. Results use compressed hexadecimal. Brackets, zone IDs and dotted subnet masks are not accepted.
Are large IPv6 counts accurate?
Yes. Address arithmetic uses BigInt, and counts are exported as decimal strings without floating-point rounding.
What happens with IPv4 /31 and /32?
A /31 has two point-to-point endpoints and no broadcast in this calculator. A /32 is one host. Prefixes below 31 subtract the network and broadcast addresses for the conventional usable host count.
Does IPv6 have a broadcast address?
No. The last mathematical address is shown as a range endpoint, not a broadcast. A mathematical count does not mean every address should be assigned.
Can I divide a network into smaller subnets?
Yes. Enter a child prefix at least as large as the parent prefix. The first 64 subnets are previewed and the total child count is reported exactly.
Does it find devices or query DNS?
No. It only performs arithmetic on the addresses you supply. No packets are sent and no address availability or routing is tested.
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