# Subnetic

> See the bits as you subnet

- Product page: https://obelisk.club/subnetic
- Platforms: iPhone
- Release status: live
- Last updated: 2026-07-17T12:36:38Z
- Pricing: free to download; the App Store listing shows any in-app purchase or subscription
- Download (iPhone): https://apps.apple.com/app/id6782267852
- Publisher: Obelisk Club (https://obelisk.club) — local-first, privacy-respecting apps built in native Swift

## About

Subnetic answers a subnet question on one screen and shows its working. Type an address with a prefix, with a mask, or on its own, and the network, broadcast, mask, wildcard and usable host range appear at once — with the binary laid out beneath them.

— WHAT MAKES SUBNETIC DIFFERENT —
• A prefix slider with the bits drawn under it
  Drag from /0 to /32 and the network bits and host bits redraw live. It is the quickest way to see what a prefix actually means.
• Three ways to type an address
  Address with a slash, address with a mask, or a bare address. All three parse.
• The awkward cases handled
  A /31 point-to-point link is reported properly instead of as a subnet with no usable hosts, and every address is labelled loopback, link-local, private, public, multicast or reserved.
• Split a block, evenly or by need
  Pro divides a block into equal subnets at a new prefix, or runs a largest-first allocation against a list of host counts.
• IPv6 as well
  Pro expands and compresses IPv6 addresses and counts the addresses in blocks far larger than a 64-bit number holds.

— PRICING —
Included: the IPv4 calculator, the binary breakdown and the prefix slider, with no cap on how often you use them.
Subnetic Pro is a one-time in-app purchase, never a subscription. It adds the subnet splitter, variable-length allocation, the IPv6 calculator and copy-all-results.

— FEEDBACK —
Made by a small indie team. Email obeliskclubclub@gmail.com with feedback, bug reports, or feature requests.

Terms of Use (EULA): https://obelisk.club/subnetic/terms

## Key features

- **Prefix slider from /0 to /32 with live binary breakdown**
- **Network, broadcast, mask, wildcard and usable host range**
- **Accepts a slash prefix, a dotted mask, or a bare address**
- **Correct handling of /31 point-to-point links**
- **Pro: equal subnet splitting and largest-first allocation**
- **Pro: IPv6 expansion, compression and address counts**

## Frequently asked questions

### How do I calculate a /26 subnet?

A /26 uses 26 network bits, giving a subnet mask of 255.255.255.192 and 64 addresses per subnet — 62 of them usable for hosts after subtracting the network and broadcast addresses. In Subnetic you can type any address with /26 (or drag the prefix slider to 26) and instantly see the network, broadcast, mask, wildcard, and usable host range, along with a live binary view showing exactly which bits are network and which are host.

### What is CIDR notation and how does it relate to a subnet mask?

CIDR notation writes an address followed by a slash and the number of network bits, like 192.168.1.0/24 — the /24 is shorthand for the mask 255.255.255.0. It replaced classful addressing so networks can be sized to fit rather than locked to Class A, B, or C boundaries. Subnetic accepts both prefix and dotted-mask input and converts between them as you type.

### Does a subnet calculator need an internet connection?

No — subnetting is pure arithmetic on the address bits, so there is nothing to look up online. Subnetic runs 100% on-device with no accounts, no network calls, and no tracking, which also means it works in exactly the places network engineers tend to need it: data centers, labs, and sites where the network is down.

### Can Subnetic split a network into smaller subnets with VLSM?

Yes. The Subnet Splitter in Subnetic Pro can divide a block into equal subnets or pack it by host requirement using VLSM, so each subnet gets just the space it needs. Pro is a one-time purchase, not a subscription, and also adds a full IPv6 calculator and export/copy-all.

### How many usable hosts are in a /31 or /32 network?

A /32 is a single host address, and a /31 has only two addresses — under classic rules that left zero usable hosts, but RFC 3021 allows both addresses of a /31 to be used on point-to-point links. Subnetic is RFC 3021 and /32 aware, so it reports these edge cases correctly instead of showing a misleading zero.