Question 1

What is Subnet Mask Calculator?

Accepted Answer

A subnet mask calculator converts between dotted-decimal subnet masks and CIDR prefix length, then computes network address, broadcast address, total addresses, and usable hosts for an IPv4 address.

Question 2

How does the Subnet Mask Calculator work?

Accepted Answer

Enter an IPv4 address and either a subnet mask (e.g. 255.255.255.0) or a CIDR prefix (e.g. /24). The tool validates contiguous mask bits, derives the prefix, and applies bitwise AND/OR to find network and broadcast ranges.

Question 3

How do I use the Subnet Mask Calculator?

Accepted Answer

Type the IP octets, then enter the mask or pick a CIDR prefix shortcut (/8, /16, /24, /28, /30, /32). Results update live. Copy the mask, CIDR block, or a share link for labs and study groups.

Question 4

How do I find the subnet mask from CIDR?

Accepted Answer

Map the prefix to 32 bits of 1s then 0s. /24 → 255.255.255.0, /28 → 255.255.255.240, /16 → 255.255.0.0. Enter the slash value in this calculator to see the dotted mask instantly.

Question 5

What is the subnet mask for /24?

Accepted Answer

The subnet mask for /24 is 255.255.255.0. It leaves 8 host bits, so each subnet has 256 addresses and typically 254 usable hosts (network and broadcast reserved).

Question 6

How many hosts does each subnet support?

Accepted Answer

Total addresses = 2^(32−prefix). Usable hosts are usually total − 2 (except /31 point-to-point and /32 single host). Example: /24 → 254 usable; /30 → 2 usable; /28 → 14 usable.

Question 7

How is a subnet mask calculated?

Accepted Answer

A subnet mask is a contiguous string of network 1-bits followed by host 0-bits. For prefix P, set the first P bits to 1 and the rest to 0, then group into four octets (0–255).

Question 8

Can this calculate network and broadcast addresses?

Accepted Answer

Yes. Network address = IP AND subnet mask. Broadcast = network OR wildcard mask. First and last usable IPs are shown for standard subnets, with /31 and /32 handled for point-to-point and host routes.

Question 9

Is this Subnet Mask Calculator free to use?

Accepted Answer

Yes. This free online subnet mask calculator runs in your browser with no signup — suitable for beginners, CCNA students, IT students, and network administration tasks.

Question 10

Can I use the Subnet Mask Calculator on mobile?

Accepted Answer

Yes. The layout works on phones and tablets so you can calculate subnet masks during exams, fieldwork, or home-network setup.

Subnet Mask Calculator

Free Online Subnet Mask Calculator for IPv4

How to find the subnet mask from CIDR

Subnet Mask FAQ

Subnet Mask Calculator — Free Online IPv4 CIDR to Subnet Mask Tool

Subnet Mask Calculator

Free Online Subnet Mask Calculator for IPv4

How to find the subnet mask from CIDR

Subnet Mask FAQ