# Support – Subnet Calculator

Welcome to the support page for **Subnet Calculator**. Here you can find answers to common questions, learn how to use the app, and get in touch with us for help or feedback.

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## Frequently Asked Questions

### General

**Q: What is Subnet Calculator?**  

A: Subnet Calculator is a network utility for developers, IT professionals, and students. It calculates subnet information from any IP address and CIDR prefix. Enter an IPv4 or IPv6 address, set the prefix length, and get network address, subnet mask, usable IP range, broadcast address, and more—all on your phone or tablet.

**Q: What platforms does the app support?**  

A: The app runs on iOS and Android.

### Using the Calculator

**Q: How do I calculate subnet information?**  

A: Select **IPv4** or **IPv6** at the top, enter an IP address (e.g. `192.168.1.100` or `2001:db8::`), adjust the **CIDR** slider to the desired prefix length, and the results appear below.

**Q: What does CIDR mean?**  

A: CIDR (Classless Inter-Domain Routing) is the number of bits used for the network portion of the address. For IPv4, common values are /24 (256 addresses) and /16 (65,536 addresses). For IPv6, /64 is typical. Use the slider to change it.

**Q: What information does the app show?**  

A: For **IPv4**: Network Address, Subnet Mask, Type (Class A/B/C/D/E), Wildcard Mask, Broadcast Address, First and Last Usable IP, IP Range, Total Addresses, Usable Hosts, and CIDR Notation. For **IPv6**: Network Address, Prefix Length, First and Last Address, IP Range, Total Addresses, and CIDR Notation.

**Q: How do I copy a value?**  

A: Long-press any result row (e.g. Network Address, Subnet Mask) to copy that value to the clipboard. A confirmation message will appear.

### IPv4 vs IPv6

**Q: What is the difference between IPv4 and IPv6?**  

A: IPv4 uses 32-bit addresses (e.g. `192.168.1.1`) and CIDR from /0 to /32. IPv6 uses 128-bit addresses (e.g. `2001:db8::1`) and CIDR from /0 to /128. Switch between them using the IPv4/IPv6 chips at the top.

**Q: Why does it say "Invalid IPv4 address" or "Invalid IPv6 address"?**  

A: The address format is invalid. For IPv4, use four octets (e.g. `192.168.1.1`). For IPv6, use hexadecimal groups separated by colons (e.g. `2001:db8::1`). Check for typos and extra spaces.

### CIDR /0 and Large Subnets

**Q: What does CIDR /0 mean?**  

A: CIDR /0 represents the entire address space. For IPv4 it is 0.0.0.0/0 (all 4 billion addresses). For IPv6 it is ::/0. The app shows a short explanation instead of listing every address.

**Q: Why are some subnets slow or not showing all hosts?**  

A: Very large subnets (e.g. /12 or /10 for IPv4) have millions of addresses. The app computes the first and last usable IP and the range without iterating over every address, so it stays fast and responsive.

### Troubleshooting

**Q: The app shows "Enter an IP address".**  

A: Type an IP address in the input field. The calculator needs at least one valid address to compute results.

**Q: How do I switch between light and dark mode?**  

A: Tap the sun/moon icon in the top-right of the app bar to toggle the theme.

**Q: Can I use the app offline?**  

A: Yes. All calculations run locally on your device. No internet connection is required.

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## Need Help?

You can reach us by email or phone. Please describe your question or issue in detail so we can assist you quickly. We typically respond within 24–48 hours.

**Email:** shrimpstudio435@gmail.com  

**Phone:** +852 6464 3622

**Feedback:** Use the form below to report bugs, suggest features, or share your opinion. We read every submission.

Thank you for using Subnet Calculator.