IP Address Range Calculator
Address counts across prefixes.
Enter your values
Results update instantly as you type — no submit needed.
Results
- Subnets available
- 256
- Addresses in parent
- 65,536
- Addresses per child
- 256
- Usable hosts per child
- 254
Quick answer
Each bit added to a prefix halves the number of addresses in the block.
Addresses = 2^(32 − prefix)
How to use the IP Address Range Calculator
- 1Enter the parent prefix you own.
- 2Enter the child prefix you want to carve out.
- 3Read how many subnets you get.
Frequently asked questions
How many /24s in a /16?
256.
Does IPv6 work the same?
The maths is identical but with 128 bits instead of 32.