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CIDR Calculator

Calculate IP address ranges from CIDR notation. Convert between CIDR, subnet masks, and IP ranges. Essential for configuring SPF records and understanding IP allowlists.

CIDR Calculator

Calculate IP ranges from CIDR notation

CIDR Notation

192.168.1.0/24

Network Address

192.168.1.0

Broadcast Address

192.168.1.255

First Usable Host

192.168.1.1

Last Usable Host

192.168.1.254

Subnet Mask

255.255.255.0

Wildcard Mask

0.0.0.255

Total IPs

256

Usable Hosts

254

SPF Record Format

ip4:192.168.1.0/24

Common CIDR Ranges

/32 = 1 IP (single host)

/30 = 4 IPs (point-to-point)

/24 = 256 IPs (Class C)

/16 = 65,536 IPs (Class B)

About this tool

This free utility is designed to help email marketers and developers improve their deliverability and campaign performance. At Sequenzy, we believe in providing transparent, helpful tools for the community.

Frequently Asked Questions

CIDR (Classless Inter-Domain Routing) notation represents IP ranges compactly. For example, 192.168.1.0/24 represents all IPs from 192.168.1.0 to 192.168.1.255 (256 addresses).

SPF records use CIDR notation to authorize IP ranges. For example, 'ip4:192.168.1.0/24' authorizes all 256 IPs in that range to send email for your domain.

The number (0-32 for IPv4) indicates how many bits are fixed. /32 is a single IP, /24 is 256 IPs, /16 is 65,536 IPs. Lower numbers mean larger ranges.

Count the number of 1s in the binary subnet mask. 255.255.255.0 = 11111111.11111111.11111111.00000000 = 24 ones = /24. Our calculator handles this conversion automatically.

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