Subnet calculator (IPv4 and IPv6)
Enter an address with its prefix, such as 203.0.113.8/29 or 2001:db8::/48. See the network, usable range and size, and split it into smaller subnets.
203.0.113.8/29
- Network
- 203.0.113.8
- First usable
- 203.0.113.9
- Last usable
- 203.0.113.14
- Broadcast
- 203.0.113.15
- Wildcard mask
- 0.0.0.7
- CIDR
- /29
- Address type
- Documentation (example addresses)
A /29 is what DediGermany's IPv4 subnet add-on gives you: 8 addresses, 6 of them usable for your services.
How subnets are counted
The number after the slash is the prefix length: how many leading bits are fixed. An IPv4 address has 32 bits, so a /29 leaves 3 bits for hosts, which is 23 = 8 addresses. The first is the network address and the last the broadcast address, so 6 are usable. A /31 is the exception: on point-to-point links both addresses are used (RFC 3021).
IPv6 addresses have 128 bits, and a single LAN is normally a /64, which is 264 addresses. Providers hand out /64, /56 or /48 networks; a /48 contains 65,536 networks of /64.
IP addresses on DediGermany servers
- Every server has one IPv4 address and its own /64 IPv6 network.
- Extra single IPv4 addresses are $3 a month each, up to 6 per server.
- An IPv4 /29 subnet (6 usable addresses) is $25 a month; larger subnets on request, subject to RIPE policy.
Questions
How many usable addresses does a /29 have?
Eight in total, six usable: the first is the network address and the last the broadcast address.
What is a wildcard mask?
The subnet mask with all bits flipped, for example 0.0.0.7 for a /29. Firewall rules and some routers use it instead of the mask.
Why is a /64 the normal IPv6 network size?
Address autoconfiguration (SLAAC) and many IPv6 features expect 64 bits for the interface part. Use a /64 per LAN even though it is enormous.
Does the calculator send my addresses anywhere?
No. The calculation runs entirely in your browser.
Not sure which server fits?
Tell us what you want to run. We reply around the clock, usually within the hour.