Your iPhone converts PNG to JPG without a single App Store download. Three built-in routes do the job: the Files app on iOS 16 and later, Safari paired with a browser converter, and a custom Shortcut. A typical screenshot drops from 4MB as PNG to roughly 400KB as JPG, which is the difference between an email that bounces and one that sends. This guide walks through all three methods, shows you where each saved file lands, explains how to hit an exact size like 100KB for an upload form, and ends by matching each method to the situation it suits best.

Why your iPhone keeps making PNG files

iOS records every screenshot as PNG because the format captures the screen losslessly, pixel for pixel, and Apple hard-codes that choice. No setting in Settings changes it. A full-screen grab on a recent iPhone lands between 3MB and 8MB, and the Markup tool exports as PNG too, even when you annotated a photo that started life as a JPG. Photos shot with the camera usually stay JPG (or HEIC), so the PNG pile is mostly screenshots, saved web graphics, and anything you edited with Markup. That matters because plenty of websites reject PNG outright or cap uploads at sizes a raw screenshot blows straight past. Converting to JPG fixes both problems at once.

Method 1: convert with the Files app

Files app conversion needs iOS 16 or later and finishes in about ten seconds:

Open Photos and find the PNG you want.
Tap the Share icon, then Save to Files, and pick a folder.
Open the Files app and press and hold the saved image.
Tap Quick Actions, then Convert Image.
Choose JPEG, then pick a size: Small, Medium, Large, or Actual Size.
The JPG appears in the same folder, beside the original PNG.

The four size buttons are the only control you get. Small shrinks the dimensions hard, Actual Size keeps them, and there's no quality slider and no file size preview before you commit. For casual sharing that's fine. For a passport portal that demands "between 20KB and 100KB", it's a guessing game, because you can't see the result's weight until after it saves. When an exact target matters, skip ahead to the Safari method.

Method 2: convert in Safari with a browser tool

Safari covers everything the Files app can't. Open the PNG to JPG converter in Safari and you get batch support for up to 50 images at once, a quality slider, and Target Size presets of 50KB, 100KB, 200KB, and 500KB. The conversion runs through the HTML5 Canvas API inside Safari itself, so your screenshots and documents never leave the handset. Files up to 25MB each are accepted, which covers even long scrolling-screenshot captures.

The steps mirror the desktop flow:

Open the converter page in Safari and tap inside the drop area.
Pick your PNGs from Photos or Files. Select several to convert a batch.
Choose Quality mode, or switch to Target Size and tap the cap your form needs.
Tap Convert, then Download each JPG or grab them all together.

Because the work happens on-device, this method suits sensitive material like ID scans and bank statements, the same files you'd never want to hand to an unknown server.

Method 3: build a one-tap Shortcut

Shortcuts pays off for anyone converting images week after week. You build it once, then trigger it from the Share Sheet forever:

Open the Shortcuts app and tap the plus button to create a new shortcut.
Add the Select Photos action (or Receive Images From Share Sheet, to run it on whatever you're viewing).
Add Convert Image and set the format to JPEG.
Add Save to Photo Album, then name the shortcut and tap Done.

From then on, converting is a single tap inside the Share Sheet, with no app to open and no page to load. The trade-off is the same as the Files app: Shortcuts gives you JPEG output but no fine control over the final file size, so it's built for speed, not for squeezing under a strict cap.

How to hit an exact file size for a form

Forms are where most iPhone conversions go wrong. Government portals, exam boards, and job sites routinely cap uploads at 100KB, the single most common limit, and a 5MB screenshot fails the check instantly. Neither the Files app nor Shortcuts can target a size, so this is the Safari method's moment. Open the converter, switch to Target Size mode, and tap 100KB (or type a custom value like 80KB). The tool runs a binary search across quality levels and hands back the sharpest JPG that still fits under your limit. Crop away empty margins first when you can, because fewer pixels mean higher quality at the same file weight. For ID photos and scanned documents, that one habit often makes the difference between a crisp result and a blurry one.

Which method should you use?

Match the method to the task:

Single file, in a hurry: Files app. Fastest path for a one-off, no page to load.
Batches or strict size caps: Safari converter. The only route with a target-size control and bulk support.
Same conversion every week: Shortcuts. Build it once, then it's a single Share Sheet tap.

Many people end up using two: a Shortcut for quick everyday JPGs, and the Safari converter whenever a form sets a hard limit.

Where the converted JPG ends up

Each route saves to a different spot, which trips people up more than the conversion itself. The Files app drops the new JPG in the same folder as the original. Safari sends downloads to the Downloads folder by default, and a long-press on the file lets you move it into Photos. A Shortcut with Save to Photo Album writes straight to your camera roll. If a converted file seems to vanish, check the Downloads folder in Files first, since that's where Safari quietly puts it.

Common problems and quick fixes

Two snags account for most failed conversions. First, Convert Image missing from Quick Actions means the device runs iOS 15 or earlier, where the feature doesn't exist; use Safari or Shortcuts instead. Second, a converted file that's still too big for a form usually came from the Files app or a Shortcut, neither of which targets a size. Reconvert it through the Safari tool in Target Size mode and the problem disappears. And if an image looks soft after conversion, the original was probably downscaled too far, so start from the full-resolution PNG rather than a shrunken copy.

Frequently asked questions

Can I convert PNG to JPG on iPhone without any app?

Yes. Three built-in methods do it: Files app Quick Actions, Safari with a web converter, and a Shortcuts workflow. None requires an App Store download.

Is JPG different from JPEG?

No, JPG and JPEG are the same format. The three-letter spelling survives from old Windows filename limits; the files themselves are byte-for-byte identical.

Does this work on iOS 15?

Partly. Safari and Shortcuts both run on iOS 15, but Files app image conversion arrived in iOS 16, so older devices have two routes rather than three.

Which methods let me convert several photos at once?

The Safari converter and Shortcuts handle batches; the Files app converts one image at a time. Safari takes up to 50 files in a single pass.

Is a Safari-based converter safe for private screenshots?

Yes, when the tool processes locally. The Canvas API runs inside Safari on your phone, and you can prove it: turn on Airplane mode after the page loads and conversion still works, because nothing is uploaded.

What happens to a transparent PNG when I convert it?

The see-through areas get filled with a solid colour, white by default, because JPG has no alpha channel. Keep the file as PNG when the transparency matters.

Is the Files app or the Safari tool better for upload forms?

The Safari tool, clearly. Only it can target a size like 100KB, while the Files app gives you four fixed buttons and no preview of the final weight.

How much smaller will my screenshot get?

Expect 60 to 90 percent smaller, depending on content. A photo-heavy screenshot compresses more than one full of text and flat colour.