How to Compress Images for Signature Uploads on iPhone

Updated May 16, 2026 · 9 min read

You do not need an app to shrink photos on an iPhone. Signature images are simple black-on-white marks, so they can be very small while staying perfectly legible.

Recommended settings for signature uploads

SettingStarting point
FormatJPEG (WebP where accepted)
Widthabout 300 px on the long edge
Quality60
File size20 KB or less

These are practical defaults. If the platform or form you are using publishes its own limits, follow those instead.

How to Compress Images

Open Safari, visit TheCompressJPEG and tap the file picker. Choose photos from your library; iOS will hand them over as JPEG even if they were shot in HEIC.

Set the target to 20 KB or a maximum width of 300 pixels, tap Compress, and save the result to Files or Photos. Everything stays on the phone, which matters for personal pictures used for signature uploads.

Step by step with TheCompressJPEG

  1. Open the compress JPEG to 20 KB tool, or the main compressor for custom settings.
  2. Drop in your image. Nothing is uploaded; it is processed in your browser.
  3. Set the maximum width to 300 and the target size to 20 KB.
  4. Press Compress, check the result and download it.
Ready to try it? Compress your JPEG to 20 KB now. It's free and private.

Quick tips

  • Use WebP where it is supported and you control the page.
  • Never re-compress an already compressed JPEG if you can avoid it.
  • Strip metadata from images you share publicly.
  • Always keep the original file and compress a copy.

FAQ

How do I compress many images for e-learning courses at once?

Drop all of them into the tool together and use Download all to get a single ZIP.

What JPEG quality should I use for e-learning courses?

Quality around 78 keeps photos looking natural while cutting file size substantially.

Will compressing reduce image quality for e-learning courses?

Some detail is removed, but at sensible settings the difference is not visible at normal viewing size.

Wrapping up

For signature uploads, the reliable recipe is simple: resize to around 300 pixels, compress at quality 60 or to a 20 KB target, and check the result before you upload. Keep the original so you can always start again.

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