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🧮 Subnet / CIDR Calculator
Subnetting is one of those topics every network engineer memorizes and every developer relearns three times. This calculator does the math. Type any CIDR block — 10.0.0.0/16, 192.168.1.0/24, whatever — and get the network address, broadcast, mask, host range, and total host count.
Examples
192.168.1.0/24Mask 255.255.255.0 · 254 hosts · 192.168.1.1 – 192.168.1.25410.0.0.0/16Mask 255.255.0.0 · 65,534 hosts · 10.0.0.1 – 10.0.255.254Frequently asked questions
What does /24 mean?
The first 24 bits identify the network, leaving 8 bits for hosts. /24 = 256 addresses (254 usable). /16 = 65,536. /30 = 4 (2 usable for point-to-point).
Why two unusable addresses?
The first (network) and last (broadcast) are reserved on standard subnets. Special exceptions: /31 (RFC 3021) and /32 treat both as usable.
About this calculator
Subnet / CIDR Calculator runs entirely in your browser using standard formulas. No data is sent to any server. We don't share your inputs with lenders, brokers, or anyone else — there's no funnel and no follow-up email.
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Why this tool
vs typical free network-tools sites
| NetToolset | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for advanced features) |
| Ads inside the tool | No | Yes (banner + interstitial) |
| Logs your IP / queries | No | Yes (often resold) |
| Data sent to a server | Math runs in browser; lookups hit Cloudflare DoH directly | Yes (all goes through their server) |
| Open source | Yes | No |
| Bookmarkable URL per tool | Yes | Mixed |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |