Dummy GIF File Generator
Every dummy GIF file is a valid GIF89a image at the width and height you pick, padded to the exact byte size.
Sample GIF files, ready to download:
One click, exact size (1 KB = 1,024 bytes), default options, built in your browser.
A dummy GIF file is a valid GIF image made for testing, drawn at the width and height you choose. Download one free at the exact size you need, up to 50 MB, at 800 x 500 pixels by default or anything up to 4096 x 4096. The picture stays the same at every file size, because the extra bytes go into a comment block that viewers ignore. For photos, use a dummy JPG file; for lossless images, a dummy PNG file.
How we check it: every generated file must be exactly the size you set and pass our own GIF parser and LZW decoder (width, height, every pixel); the last run on 13 November 2026 passed 223 of 223 runs across 22 formats, and every sample also decoded in headless Microsoft Edge (21 of 21 browser cases) (how the files are made and checked).
What is inside a dummy GIF file
A standard GIF89a file, built without a canvas (how we build and check these files):
- An image of exactly the width and height you set: diagonal blue stripes, a white band across the middle and a 1-pixel dark border.
- A four-colour palette, compressed with the standard GIF LZW method.
- A comment block after the image that carries the extra bytes. It holds plain text, so the file is padded inside the format, not with zeros after the end.
- One frame: the GIF is not animated and has no transparency.
What a dummy GIF file is used for
Image upload limits
Test size caps on avatar, attachment and media uploads with a GIF of an exact byte count.
Allow lists
Check that your upload filter accepts image/gif when it should, and rejects it where only PNG or JPG are allowed.
Dimension rules
Set the width and height to test minimum and maximum dimension checks, separately from the file size.
Thumbnails and conversion
Feed GIFs to thumbnailers and converters and confirm the output has the expected size.
File size and pixel size are two different tests
A GIF of 800 x 500 pixels can be 10 KB or 10 MB here: the dimensions set the picture and the byte size sets the padding. Test them separately. A form that limits uploads to 5 MB and images to 4000 pixels wide needs both a 5 MB file at a small size and a small file that is too wide.
The smallest possible file depends on the dimensions, because the picture itself takes space. If the size you ask for is too small, the tool tells you the minimum for those dimensions.
| Limit | Size | Notes |
|---|---|---|
| nginx client_max_body_size (default) | 1 MB 1,048,576 B | Requests with a larger body get HTTP 413. |
| PHP upload_max_filesize (default) | 2 MB 2,097,152 B | Also capped by post_max_size, so raise both. |
| AWS Lambda synchronous invocation payload | 6 MB 6,291,456 B | Applies to request and response. |
| Amazon API Gateway REST API payload | 10 MB 10,485,760 B | Hard quota for REST APIs. |
| Outlook default attachment limit (Exchange accounts) | 10 MB 10,485,760 B | Administrators can change it. |
| Outlook attachment limit (internet accounts) | 20 MB 20,971,520 B | Per Microsoft Outlook guidance. |
| Gmail message size limit | 25 MB 26,214,400 B | Attachments grow about a third when encoded, so a 20 MB file can already be too big. |
GIF file details
- Extension
- GIF .gif
- MIME type
- image/gif
- Smallest size
- 100 Bytes
- Largest size
- 50 MB
- Contents
- GIF89a image at the width and height you choose (default 800 x 500), 4 colours, LZW-compressed; extra size is a comment block
Dummy GIF file FAQ
Is the dummy GIF a real image?
Yes. It is a standard GIF89a that browsers decode at the width and height you chose. We check it with our own LZW decoder and in a real browser.
Is the dummy GIF animated?
No. It has a single frame and no transparency. Use it for upload, size and dimension tests, not for animation playback.
Can I choose the width and height?
Yes. Open Options and set the width and height in pixels, from 1 to 4,096 each; the default is 800 x 500. If the size is too small for those dimensions, the tool says the minimum.
How is the exact file size reached?
A comment block after the image holds the extra bytes. Viewers ignore comments, so the picture looks the same at any file size.
What is the MIME type of a GIF?
image/gif. The file starts with the bytes GIF89a, which is what most upload checks look for.
How large can a dummy GIF file be?
Up to 50 MB, with dimensions up to 4096 x 4096 pixels. Very large images can take a few seconds to build.
Is the image uploaded anywhere?
No. It is drawn and encoded in your browser and never sent to a server.