NetDevKit: Network & Developer Calculators
Fast, Private, Browser-Only Network & Developer Calculators. Every tool runs locally inside your browser for instant speed and complete privacy.
Networking
IPv4 Subnet & CIDR Calculator
Calculate network address, broadcast, usable host range, wildcard mask, and binary representation instantly.
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Networking
VLSM Subnet Splitter
Allocate variable-length subnet masks efficiently across departments or cloud VPCs without wasting IPs.
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Cloud & Infra
Bandwidth & File Transfer Time Calculator
Estimate exact download/upload durations across Mbps, Gbps, MB/s, and cloud link overheads.
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DevOps
Cron Expression Explainer & Simulator
Translate 5-field Linux/Kubernetes cron schedules into plain English and preview upcoming execution times.
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Developer
Private JSON & Base64 Formatter
Format, minify, validate JSON and encode/decode Base64 100% locally in your browser with zero server uploads.
Open Tool →IPv4 CIDR Subnet Mask Quick Reference (/8 to /32)
Select any CIDR prefix below for its exact subnet mask, wildcard mask, usable host count, and binary layout.
| CIDR | Subnet Mask | Wildcard Mask | Total IPs | Usable Hosts | Common Use |
|---|---|---|---|---|---|
| /8 | 255.0.0.0 | 0.255.255.255 | 16,777,216 | 16,777,214 | Legacy Class A supernets, large ISP backbones, and private 10.0.0.0/8 enterprise allocation. |
| /9 | 255.128.0.0 | 0.127.255.255 | 8,388,608 | 8,388,606 | Custom CIDR block with 8,388,608 total IPv4 addresses (8,388,606 usable host IPs) for VLSM allocation. |
| /10 | 255.192.0.0 | 0.63.255.255 | 4,194,304 | 4,194,302 | Custom CIDR block with 4,194,304 total IPv4 addresses (4,194,302 usable host IPs) for VLSM allocation. |
| /11 | 255.224.0.0 | 0.31.255.255 | 2,097,152 | 2,097,150 | Custom CIDR block with 2,097,152 total IPv4 addresses (2,097,150 usable host IPs) for VLSM allocation. |
| /12 | 255.240.0.0 | 0.15.255.255 | 1,048,576 | 1,048,574 | Custom CIDR block with 1,048,576 total IPv4 addresses (1,048,574 usable host IPs) for VLSM allocation. |
| /13 | 255.248.0.0 | 0.7.255.255 | 524,288 | 524,286 | Custom CIDR block with 524,288 total IPv4 addresses (524,286 usable host IPs) for VLSM allocation. |
| /14 | 255.252.0.0 | 0.3.255.255 | 262,144 | 262,142 | Custom CIDR block with 262,144 total IPv4 addresses (262,142 usable host IPs) for VLSM allocation. |
| /15 | 255.254.0.0 | 0.1.255.255 | 131,072 | 131,070 | Custom CIDR block with 131,072 total IPv4 addresses (131,070 usable host IPs) for VLSM allocation. |
| /16 | 255.255.0.0 | 0.0.255.255 | 65,536 | 65,534 | Class B networks, major cloud VPC primary blocks (e.g., AWS/GCP 10.0.0.0/16), and university campuses. |
| /17 | 255.255.128.0 | 0.0.127.255 | 32,768 | 32,766 | Custom CIDR block with 32,768 total IPv4 addresses (32,766 usable host IPs) for VLSM allocation. |
| /18 | 255.255.192.0 | 0.0.63.255 | 16,384 | 16,382 | Custom CIDR block with 16,384 total IPv4 addresses (16,382 usable host IPs) for VLSM allocation. |
| /19 | 255.255.224.0 | 0.0.31.255 | 8,192 | 8,190 | Custom CIDR block with 8,192 total IPv4 addresses (8,190 usable host IPs) for VLSM allocation. |
| /20 | 255.255.240.0 | 0.0.15.255 | 4,096 | 4,094 | Medium-to-large regional VPC subnets supporting up to 4,094 hosts per availability zone. |
| /21 | 255.255.248.0 | 0.0.7.255 | 2,048 | 2,046 | Custom CIDR block with 2,048 total IPv4 addresses (2,046 usable host IPs) for VLSM allocation. |
| /22 | 255.255.252.0 | 0.0.3.255 | 1,024 | 1,022 | Corporate office floors or Kubernetes pod CIDRs requiring ~1,000 IP addresses. |
| /23 | 255.255.254.0 | 0.0.1.255 | 512 | 510 | Custom CIDR block with 512 total IPv4 addresses (510 usable host IPs) for VLSM allocation. |
| /24 | 255.255.255.0 | 0.0.0.255 | 256 | 254 | Standard Class C LAN subnet, home/office routers, and typical production microservice tiers (254 hosts). |
| /25 | 255.255.255.128 | 0.0.0.127 | 128 | 126 | Half of a /24 block—ideal for splitting a standard office LAN into two isolated VLANs. |
| /26 | 255.255.255.192 | 0.0.0.63 | 64 | 62 | Quarter of a /24 block (62 usable hosts)—common for DMZs or small department VLANs. |
| /27 | 255.255.255.224 | 0.0.0.31 | 32 | 30 | Small server rack or Kubernetes node pool (30 usable hosts). |
| /28 | 255.255.255.240 | 0.0.0.15 | 16 | 14 | Cloud NAT gateways, bastion subnets, or small database tiers (14 usable hosts). |
| /29 | 255.255.255.248 | 0.0.0.7 | 8 | 6 | Tiny firewall transit segments or multi-router HA VIP pools (6 usable hosts). |
| /30 | 255.255.255.252 | 0.0.0.3 | 4 | 2 | Traditional point-to-point WAN router links (2 usable hosts). |
| /31 | 255.255.255.254 | 0.0.0.1 | 2 | 2 | Modern RFC 3021 point-to-point router interconnect link (2 usable hosts, zero wasted broadcast). |
| /32 | 255.255.255.255 | 0.0.0.0 | 1 | 1 | Single host route, loopback interface, or exact firewall /32 allowlist rule. |