# How to send ISO files

ISO (Optical disc image) files are often too big for email and chat apps. Here is how big they get and how to send them exactly as they are.

_Source: https://sharelargefilesfree.com/send-iso-files · Updated 2026-10-13_

**Quick answer:** To send a large ISO file, upload it to Share Large Video Files (up to 20 GB, no account) and share the download link: the file arrives unchanged. An OS installer ISO is about 4.9 GB, more than most email providers accept.

## What is a ISO file?

An ISO is a complete image of a CD, DVD or Blu-ray, stored as one file. Operating system installers (Windows, Linux), software installation media, bootable rescue tools and archived discs are distributed as ISOs.

Size follows the disc it represents: up to about 700 MB for a CD, 4.7 GB for a single-layer DVD, 8.5 GB for a dual-layer DVD and 25 GB or more for a Blu-ray. Modern OS installers sit in the 2 to 7 GB range.

Extensions: .iso, .img.

## How big are ISO files?

| File | Typical size |
| --- | --- |
| A CD image | up to about 700 MB |
| A Linux distribution installer | roughly 1 to 6 GB |
| A Windows 11 installer | roughly 5 to 7 GB |
| A single-layer DVD / dual-layer DVD image | up to about 4.7 GB / 8.5 GB |
| A Blu-ray image | about 25 GB (single layer) or 50 GB (dual layer) |

## Which apps can send one?

Can you send an OS installer ISO (about 4.9 GB) as an attachment?

| App | Limit | Fits? |
| --- | --- | --- |
| Gmail | 25 MB per email | No, send a link |
| Outlook.com | 20 to 25 MB per email | No, send a link |
| WhatsApp (document) | 2 GB per file | No, send a link |
| Telegram | 2 GB per file | No, send a link |
| Facebook Messenger | 100 MB per file | No, send a link |
| Discord (free) | 20 MB per file | No, send a link |
| Slack | 1 GB per file | No, send a link |
| WeTransfer (free) | 3 GB per transfer | No, send a link |
| **Share Large Video Files** | 20 GB per transfer | Send the link anywhere |

Limits from our [file size limits by app](https://sharelargefilesfree.com/file-size-limits-by-app) table, checked against each service's help pages.

## How to send ISO files without changing them

1. Open [Share Large Video Files](https://sharelargefilesfree.com/) in any browser and choose **Get a link** (or **Send by email**).
2. Drop ISO files on the upload box, or pick a whole folder. Up to 20 GB and 1000 files per transfer.
3. Optional: add a password, a download limit or an expiry under More options.
4. Copy the link (or show the QR code) and send it by chat or email. The recipient downloads the original file, byte for byte.

## Tips for sending ISO files

- Share a SHA-256 checksum so the recipient can confirm the ISO downloaded without errors.
- Only share images of software and discs you have the right to distribute.
- Do not zip an ISO of video discs expecting big savings; the contents are already compressed.
- FAT32 USB drives cannot store files over 4 GB, so the recipient may need exFAT or NTFS for large ISOs.

## How to open a ISO file

**Windows 8 and later:** double-click to mount the ISO as a virtual drive. **Mac:** double-click to mount it in Finder. To make a bootable USB stick, use tools such as Rufus (Windows) or balenaEtcher (Windows, Mac, Linux). Phones cannot use ISOs directly.

## Frequently asked questions

### How do I open an ISO file?

On Windows and Mac, double-click it to mount it as a virtual disc and browse the files. To install an OS, write it to a USB stick with a tool such as Rufus or balenaEtcher.

### How can I check an ISO downloaded correctly?

Compare its SHA-256 checksum with the one provided by the sender. If they match, the file is identical.

### Why can't I copy my ISO to a USB stick?

The stick is probably formatted as FAT32, which cannot hold files over 4 GB. Reformat it as exFAT or NTFS.