HEIC vs JPG: The 50% Smaller Claim Only Holds at Some Quality Settings
HEIC saves 23-30% over JPG at quality 80, but almost nothing at quality 90. Measured on four images with PSNR, plus what you actually lose converting HEIC to JPG.
Short answer: HEIC is meaningfully smaller than JPG at mid quality settings, roughly the same size at high quality settings, and the only one of the two that can store transparency. JPG wins on one thing that usually outweighs all of that — everything can open it.
The “HEIC is 50% smaller” line gets repeated a lot. I wanted to know at which settings that is actually true, so I encoded four images to both formats at four quality levels with macOS’s own encoder (the same HEIC implementation the iPhone uses), then decoded everything back and measured PSNR against the original to confirm I was comparing like with like.
The measurements
PSNR measures how close the decoded image is to the original — higher is better, above 40 dB is visually identical, below 30 dB shows visible damage. It matters here because a size comparison means nothing if the two files are not at comparable quality.
| Image | Size | Quality | HEIC | JPG | HEIC saves | HEIC PSNR | JPG PSNR |
|---|---|---|---|---|---|---|---|
| Photo | 1200×801 | 90 | 501 KB | 508 KB | 1% | 36.8 dB | 36.3 dB |
| Photo | 1200×801 | 80 | 326 KB | 422 KB | 23% | 35.3 dB | 35.4 dB |
| Photo | 1200×801 | 70 | 270 KB | 363 KB | 26% | 34.4 dB | 34.4 dB |
| Photo | 1200×801 | 60 | 216 KB | 280 KB | 23% | 33.3 dB | 33.0 dB |
| Portrait | 614×407 | 90 | 121 KB | 121 KB | 0% | 37.5 dB | 38.2 dB |
| Portrait | 614×407 | 80 | 68 KB | 97 KB | 30% | 36.1 dB | 37.2 dB |
| Portrait | 614×407 | 70 | 56 KB | 83 KB | 32% | 35.4 dB | 36.1 dB |
| Flat graphic | 1200×630 | 80 | 67 KB | 130 KB | 49% | 33.5 dB | 34.5 dB |
Two things fall out of this that the usual comparison misses.
The saving collapses at quality 90. On the photo, HEIC saved 1%. On the portrait, 0% — the two files landed within 44 bytes of each other. HEIC’s advantage lives in the mid range, where its smarter prediction has room to work. Push both encoders toward visually lossless and they converge.
At quality 80 the PSNR figures are near-identical (35.3 vs 35.4 on the photo), so that 23% saving is a genuine like-for-like win, not HEIC quietly throwing away more detail. On the portrait, JPG actually scored higher (37.2 vs 36.1) while being 30% larger — so HEIC’s saving there comes partly from accepting slightly more loss.
What conversion actually costs you
The practical question is not which format is better in the abstract. It is what happens when you convert the HEIC your phone produced into something you can actually send. I encoded each source to HEIC at quality 80, then re-encoded that file to JPG the way a converter would:
| Source | HEIC (q80) | → JPG q90 | → JPG q80 |
|---|---|---|---|
| Photo | 334 KB | 505 KB (+51%) | 417 KB (+24%) |
| Portrait | 70 KB | 115 KB (+65%) | 94 KB (+35%) |
So a converted photo lands 24-35% larger at matching quality, or 51-65% larger if the converter exports at quality 90 (a common default, chosen to avoid visibly degrading an already-compressed image).
That is the real trade: you give up roughly a third of the storage saving to get a file that opens anywhere. For a handful of photos you are emailing, that is a fine trade. For your entire library, it is not.
Transparency is where JPG simply cannot compete
One of my test images was a 1200×716 graphic where 84.1% of the pixels are fully transparent. Encoded to HEIC at quality 90 it came out at 11 KB with a PSNR of 52.3 dB. Encoded to JPG it came out at 46 KB — four times larger — with a PSNR of 0.7 dB.
That number is not a compression artefact. JPG has no alpha channel, so every one of those 722,247 transparent pixels got filled with an opaque colour. The image is not degraded, it is replaced.
This is the one case where the choice is not a trade-off. If your image has any transparency, JPG is not an option regardless of file size.
So which should you use
Keep HEIC when the photos stay inside the Apple ecosystem, storage matters (a full phone library at 23-30% smaller is real money in iCloud tiers), or the image has transparency.
Convert to JPG when you need to send the file somewhere. This is almost always the actual reason people search for this comparison — not size, but the fact that Windows, older Android builds, and a lot of web upload forms still reject HEIC outright. No amount of encoding efficiency helps if the recipient sees a file they cannot open.
Do not bother converting your whole library. Keep capture set to HEIC and convert the specific photos you need to share. You keep the storage saving on the thousands of photos nobody else will ever see.
If you need to convert a few right now, our HEIC to JPG converter runs entirely in your browser — the photos never leave your device, which matters more than usual given that the files people convert are typically personal camera-roll photos.
About these numbers
Encoding and decoding used macOS’s built-in sips, which uses Apple’s own HEIC implementation — the same lineage as the encoder on the iPhone. Sources were PNG originals rather than camera raw captures, so absolute byte counts will differ from your own photos. The ratios between the two formats at matching quality settings are the part that transfers.
Frequently asked questions
Is HEIC really half the size of JPG?
Not reliably. In our measurements HEIC saved 23-30% over JPG at quality 80 and 41-49% on flat graphics, but only 0-1% at quality 90. The 50% figure comes from comparing HEIC against JPG at settings most cameras do not use. The saving is real at mid quality and close to zero at high quality.
How much bigger does my photo get when I convert HEIC to JPG?
In our tests, a quality-80 HEIC re-encoded to JPG grew 24-35% at matching quality, and 51-65% if exported at quality 90. A 334 KB HEIC became a 505 KB JPG. Nothing is lost visually at those settings, but the file is meaningfully larger.
Does converting HEIC to JPG lose quality?
Yes, slightly, because both are lossy and you are re-encoding. At quality 90 the second encode adds far less damage than the original capture did. The bigger risk is transparency: JPG cannot store an alpha channel at all.
Why can't Windows open my HEIC files?
HEIC is the default capture format on iPhone but is not natively supported across Windows, older Android, and many web upload forms. That compatibility gap, not file size, is the usual reason people convert to JPG.
Should I turn off HEIC on my iPhone?
Only if you constantly hit compatibility problems. Keeping HEIC and converting the handful of photos you actually need to share preserves the storage saving on the rest of your library.