---
title: "VPC address ranges"
description: "Which address ranges a TIR VPC accepts, how many addresses each size gives you, and how to size a range that stays with the VPC for its whole life."
content_type: "concept"
product: "tir-vpc"
platform: "TIR"
url: "/tir/tir-vpc/concepts/vpc-address-ranges/"
---

# VPC address ranges

You choose a VPC's address range when you create it, and the VPC keeps that range for as long as it exists. To use a
different range, create a new VPC. Size the range for the resources you expect to have later, as well as the ones
you start with.

## What a range must look like

A range must be:

- a private IPv4 network, inside 172.16.0.0 to 172.29.255.255 or inside 192.168.0.0/16;
- between /16 and /28 in size;
- written as a network address, with the host bits at zero.

| Value             | Accepted                        |
| ----------------- | ------------------------------- |
| `172.16.231.0/24` | Yes                             |
| `192.168.0.0/16`  | Yes                             |
| `172.16.231.5/24` | No. The host bits must be zero. |
| `192.168.1.0/16`  | No. The host bits must be zero. |

The **Create VPC** form lists the ranges you can use under **Available ranges** and checks yours as you type.

### Ranges a VPC refuses

A VPC refuses three ranges, even though they are valid private ranges elsewhere: the whole `10.0.0.0/8` block,
including every range inside 10.x.x.x, `172.30.0.0/16`, and `172.31.0.0/16`.

Everything else inside 172.16.0.0 to 172.29.255.255 and 192.168.0.0/16 is available, so `172.16.231.0/24` and
`192.168.50.0/24` are both safe starting points. Two VPCs can use the same range, because each VPC is its own network.

## Picking a size

| If you expect                                | Consider                                                 |
| -------------------------------------------- | -------------------------------------------------------- |
| A handful of resources, for a test or a demo | `/27` or `/26`                                           |
| A typical project                            | `/24`, with 247 usable addresses, the most common choice |
| A large or growing deployment                | `/22` or `/20`                                           |
| Many resources in one network                | `/16`                                                    |

A `/28` leaves only seven usable addresses, which is easy to outgrow. When in doubt, take the larger range, because a range
that is too small means creating a new VPC and moving your resources.

## Reserved addresses

Every VPC sets aside nine addresses from its range for networking: the first eight and the last. In a `/24` that starts at `.0`, those are `.0` to `.7` and `.255`. For a VPC on `172.16.231.0/24`,
`172.16.231.0` to `172.16.231.7` and `172.16.231.255` are reserved, leaving `172.16.231.8` to `172.16.231.254` for your
resources.

The VPC sets these nine aside once for the whole range, so a `/16` gives up the same nine addresses that a `/28`
does.

## How many addresses you get

The **Available IPs** column in the VPC list shows free addresses over assignable ones. Assignable is every address the VPC can ever
hand out: the size of the range, less the nine reserved addresses. Free is how many of those are still unused.

| Size  | Addresses in the range | Assignable |
| ----- | ---------------------- | ---------- |
| `/16` | 65,536                 | 65,527     |
| `/20` | 4,096                  | 4,087      |
| `/22` | 1,024                  | 1,015      |
| `/24` | 256                    | 247        |
| `/26` | 64                     | 55         |
| `/27` | 32                     | 23         |
| `/28` | 16                     | 7          |

## What you can do

[Create a VPC](/tir/tir-vpc/how-to/create-a-vpc/) with the range you chose. For help with a message about the range, see
[Troubleshooting VPC](/tir/tir-vpc/troubleshooting/tir-vpc/).