Prefix Splitter
Results update as you type.
/16
/20
All Subnets
Tick the subnets you want, then pick an export format below.
| # | CIDR | Network | Broadcast | HostMin (RFC) | HostMax (RFC) |
|---|
Export
No subnets selected yet — tick a row in All Subnets above and the code appears here.
Quick Reference
The prefixes that come up day to day. Use the selectors above for anything else.
| Prefix | Total IPs | Usable Hosts (RFC) | Netmask | Typical Use |
|---|
AWS note: VPC subnets must be sized between /16 and /28 — AWS won't let you create anything smaller than a /28. AWS also reserves 5 addresses in every subnet, not 2, so subtract 5 from Total IPs to get the usable count, not the RFC figure above.