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Calculate IPv4 Subnets

Calculate IPv4 network, broadcast, and host ranges

About This Tool

IPv4 Subnet Calculator computes network address, broadcast, subnet mask, wildcard, usable host count, and host range from an IP plus CIDR or dotted mask. Useful for network planning and lab work. All calculations are processed locally in your browser.

How to Use

  1. Enter an IPv4 address
  2. Enter a CIDR prefix (e.g. 24) or dotted mask
  3. Click Calculate
  4. Review network, broadcast, and host range
  5. Clear to try another subnet

Common Use Cases

  • Networking: Plan LAN or VLAN ranges
  • Cloud: Check VPC CIDR host capacity
  • Exams: Practice subnetting problems
  • Support: Verify customer mask settings
  • Labs: Sketch ranges without a spreadsheet

FAQ

Q1: What is CIDR?

CIDR is the prefix length (e.g. /24). You can also paste a dotted mask like 255.255.255.0.

Q2: Are /31 and /32 special?

Yes. Usable host counts follow common conventions for point-to-point (/31) and single-host (/32) networks.

Q3: Is anything uploaded?

No. Subnet math is processed locally in your browser.

Q4: Why do I see an invalid error?

The IP must have four octets 0–255, and the mask must be a valid prefix or contiguous mask.

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