HEIC to JPG without losing quality: what really happens to pixels, EXIF and orientation

· Published 2026-11-11 · YYSI Editorial · 中文版

Short answer: converting HEIC to JPG always re-encodes the pixels — JPG is a lossy format, so a strictly lossless HEIC→JPG conversion does not exist. What a good converter can do: keep the pixel size 1:1, apply the rotation stored in the file, and stay visually faithful at a reasonable quality setting. What this browser converter cannot do: keep EXIF metadata — our measurements show every EXIF tag (camera, shooting date, ISO) is dropped in all output formats. Below are the real numbers so you can decide what matters for your photos.

What we tested, and how you can re-check it

We generated three original synthetic HEIC files for this guide (no third-party photos), converted them in the live HEIC converter, then inspected the downloaded outputs with an EXIF-aware image library and compared the rotated case against an independent reference decoder. The sample files are published below — every number on this page can be reproduced from them.

• Sample A — landscape photo scene, 1600×1067, with EXIF (camera, date, ISO), no GPS — Download sample · 126747 bytes
  SHA-256: ef80fcc95b72ea184c39b00d8b3f6cc391390ec4ffa5f8dd09fcba7e67dafd75
• Sample B — portrait photo stored as a rotated sensor frame (irot + EXIF Orientation 6), exactly how iPhone portrait shots are stored — Download sample · 26563 bytes
  SHA-256: b4ad2ec92edcb0534fba9587d09b0169157c4ba0c2534faf39f9b9f51aad0ac2
• Sample C — logo with real transparency (RGBA) — Download sample · 12371 bytes
  SHA-256: e7a97107f42692b8542f89e73a55173930ec6251cc170ef0e847bbc8ec95b025
• Actual tool output of sample A at JPG quality 85 (81,164 bytes) — Download sample · 81164 bytes
  SHA-256: 2689e708a673a1f8325b907c7f0383f12198196c3e9dbc09618f3406f27d9743

The answers at a glance

Step by step in the real tool

1. Open the converter. Go to the HEIC converter. It runs entirely in your browser; a WebAssembly decoder (about 2 MB, libheif-based) loads only when you first convert. Files never leave your device.
2. Add your photos. Drag files onto the drop zone or click it to choose. Up to 20 files per batch, each up to 20 MB. Extensions are never just renamed — the decoder reads the real HEIC structure.
3. Pick output format and quality. JPG (with a quality slider from 40 to 100), PNG, or WebP. For photos choose JPG quality 75–90; for logos or screenshots with transparency choose PNG or WebP.
4. Convert and download. Press Convert — each row shows the size change (for example "124 KB → 79 KB", where KB means 1024 bytes). Download single files or the whole batch as a ZIP.
5. Check what you got. Open one output and confirm the size and orientation. If you need the shooting date, copy it from the original first — the JPG will not carry it (see below).

Quality vs. file size: real measurements

Two honest conclusions from this table. First, quality 100 is not lossless — it is still JPG re-encoding, it just wastes the least. Second, a converted JPG can easily end up bigger than the HEIC you started with, because HEIC's compression is more efficient. "Smaller file" is a reason iPhones shoot HEIC, not a property of the format you convert to.

Rotated photos: orientation is applied correctly

Portrait iPhone photos are stored as a rotated sensor frame plus a rotation instruction (an irot transform in the HEIC container, usually mirrored by an EXIF Orientation tag). Our sample B is built exactly that way: 600×400 pixels stored, displayed upright as 400×600. The tool's output was 400×600 with the image upright — we verified its pixel layout (marker block and corner colors) is identical to an independent reference decode of the same file. You do not need to rotate anything before or after converting this kind of file.

Scope note: we tested the irot-style rotation that real phone portraits use. HEIC files that carry *only* an EXIF Orientation tag and no irot transform were not part of this test — if you ever meet one, glance at the corners of the output before batch-processing the rest.

EXIF metadata: dropped in every output format

This is a real limitation and a privacy feature, depending on what you need. If the shooting date matters (archives, evidence, warranty photos), record it from the original before converting — the output will not remember it. If you are posting photos publicly, the conversion silently strips location and camera details: nothing leaks from the file itself. Note that the photo *content* can still show addresses or screens with private information — metadata removal is not content redaction.

Transparency: pick PNG or WebP, not JPG

Our alpha sample (a logo with transparent corners) survived as expected: PNG and WebP outputs kept the alpha channel (corners fully transparent, RGBA), while the JPG output flattened the transparent areas to solid black — that is inherent to JPG, which has no alpha channel. Converting a transparent logo to JPG gives you black boxes where the background should show through.

Limits and failure handling

• 20 files per batch, 20 MB each — the queue rejects anything larger with a clear message.
• Live Photos export the still image (the video part of the container is not merged).
• 10-bit HDR material is tone-mapped to 8-bit output and can look slightly different (disclosed on the tool page; not part of our synthetic test set).
• Unusual HEIF variants may simply fail to decode — the tool reports the failure per file instead of silently corrupting output.
• Do not rename .heic to .jpg as a shortcut: that produces a JPG-named file containing HEIC data, which many apps refuse to open — the extension will be lying about the contents.

Why your computer may not open HEIC at all

HEIF (.heic) is the efficient photo format iPhones have used since iOS 11; Apple notes it offers better compression than JPEG (Apple Support, checked 2026-11-11). Windows 10/11 can read and write HEIF once Microsoft's HEIF Image Extension is installed from the Store (official listing, checked 2026-11-11); some files additionally need the HEVC Video Extensions. That is why the same photo opens on a Mac but shows an error on a fresh Windows installation — and why a browser-based converter is often the fastest cross-platform fix.

Which output format to choose

For everyday iPhone photos → JPG at quality 75–90 is the practical choice: full pixel dimensions, correct orientation, no surprise black boxes — and no metadata you did not decide to keep. Continue with compressing the result to an exact size limit if a form or portal rejects the file size.