kelvappA photo, a video and a PDF can all be too large for an upload, but they do not shrink in the same way. A useful starting point is the destination: which file types does it accept, and what is its size limit?
Squooshy for iPhone and iPad offers photo, video and PDF compression. This guide explains the tradeoffs without assuming every input will get smaller. Keep your original while checking the output.
Which format are you working with?
| File | What matters | Check before sharing |
|---|---|---|
| JPEG / JPG | Common for photographs; lossy encoding can reduce detail. | Faces, fine texture and small text. |
| PNG | Useful for transparency and sharp graphic edges. | Transparent areas and readable lettering. |
| HEIC | Efficient photo storage; recipient compatibility varies. | The receiving app accepts the actual output format. |
| MOV / MP4 / M4V | Containers, which can hold different video codecs. | Playback, audio, orientation and duration. |
| May contain scanned images, selectable text or vectors. | Every page, small print, search and selection. |
Changing a file extension is a new name tag, not a makeover.
A familiar extension does not guarantee a readable file. The media inside must also be supported by the device and app.
JPEG: start here for everyday photographs
JPEG is widely supported and suits photographs well. Its compression is lossy: lowering quality can discard information. A smaller copy might be suitable for a form attachment while being a poor choice for later editing or printing.
Try a balanced preset first, then inspect details at a useful viewing size. If a smaller setting makes hair, leaves or lettering look smeared, the extra reduction may not be worth it. Compressing an already compressed JPEG repeatedly can accumulate damage. Return to the original when trying another setting.
A small file is lovely. A face that looks like it was painted with a potato is less useful.
JPEG cannot store transparency. A transparent logo and a holiday photo therefore need different decisions, even if both are called images. See the MDN image-format reference for format properties.
PNG: protect transparency and sharp edges
PNG is often useful for screenshots, diagrams and artwork with transparent areas. It uses lossless compression; a JPEG-style quality reduction is not the same operation as optimizing a PNG.
A photo saved as PNG may be much larger than a visually similar JPEG, but converting it changes the tradeoff. For a logo, preserving the background transparency may matter more than reducing bytes. Check edges against both light and dark backgrounds before accepting the result.
Do not assume Squooshy will preserve the input extension or offer every conversion in your installed version. Inspect the actual saved format. Check your installed version before relying on a particular conversion option.
HEIC: efficient storage does not guarantee a smaller conversion
Apple devices commonly use HEIF images, often with a HEIC extension. These can already be efficient. Converting one to JPEG for compatibility can produce a larger file, depending on the image and encoding settings.
Apple explains HEIF and HEVC support and sharing behavior. If an upload form accepts JPEG but rejects HEIC, you have a format requirement as well as a size requirement. Confirm that your installed tools offer the needed conversion, then check the output against both requirements. Renaming .heic to .jpg does not convert an image.
Video: MP4 is the container, H.264 is a codec
MOV, MP4 and M4V describe containers. H.264 and HEVC describe video coding. Two MP4 files can contain different codecs and behave differently in a receiving app. The MDN container guide explains that distinction.
Video size depends on duration, video bitrate, audio and container overhead. A long recording usually needs a stronger tradeoff to reach the same size as a short clip. Lower resolution or bitrate can reduce size, but may also make text or motion harder to see.
The public 1.1 compression path produces H.264 MP4 at up to 1080p. Do not expect its compression path to preserve a source video's HEVC codec, 4K resolution or HDR presentation. Test a short representative clip if those properties matter. Check playback, sound, orientation and the end of the exported video before deleting or sharing anything.
PDF: a scan and a text document have different limits
A scanned PDF may contain large page images. A PDF generated from text may already be compact. These are different optimization problems, even though both end in .pdf.
Squooshy's PDF optimization rewrites the document while preserving text and vector content. It is not a general-purpose scan resizer and does not turn every page into a lower-quality picture to force savings. Some PDFs will stay the same size or offer no useful reduction. Unreadable or protected documents may be rejected.
Open the result and inspect all pages, especially small print and diagrams. If the original text was selectable or searchable, check that behavior too. Keep the original of signed or otherwise important documents; a rewritten copy should not be assumed to preserve a digital signature.
A practical compression check
- Read the receiving service's accepted formats and size limit.
- Choose a supported file in Squooshy and start with an appropriate preset or available target.
- Compare the original and output byte sizes. Targets are best effort, not guarantees.
- Open the saved copy in the app or service that will receive it.
- Keep the original until you are satisfied with the result.
If the file already meets the limit, more compression may add quality loss without helping. If no useful savings are available, use the original or choose a different sharing method.
For the first steps, read the Squooshy quickstart. For size-limit problems, use the upload-limit guide. Compression and conversion are separate operations; Squooshy is not a PDF-to-Word, audio or ZIP converter.
Get Squooshy on the App Store ↗
Checked 28 October 2026 against the public 1.1.0 listing and its available engine source. Installed features can differ by version. File support and achievable savings depend on the source and device.