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Measurement · 3 min read

Does an image get bigger when you convert HEIC to JPG?

Usually yes: converted to JPG, 20 HEIC screenshots from a MacBook Pro were 2.97 times as large at the median, and none got smaller. For 17 macOS desktop pictures, 21.75 MB as HEIC at the median, it was the other way round: as JPG they were only a third of the size at the median. Measured on October 19, 2026 with sips.

Why does a HEIC usually get bigger as a JPG?

Because HEIF compresses more efficiently than JPEG: Apple states that HEIF offers better compression than JPEG and so uses less storage (Apple Support, checked October 19, 2026). For the 20 HEIC screenshots from October 19, 2026 on the MacBook Pro, the JPG came out 1.81 to 4.08 times as large.

Interface screenshots grow more than text screenshots, and photo screenshots less.

Content HEIC JPG Factor
Text 276 KB 817 KB 2.91
Interface 204 KB 653 KB 3.40
Photo 519 KB 1.24 MB 2.28

All values are medians of the 7, 7 and 6 captures in each group, converted with sips without a quality setting. The factor is the median of the per-image factors, so it differs slightly from the ratio of the two medians.

When is the JPG smaller than the HEIC?

With large HEIC files like Apple’s desktop pictures: the 17 macOS desktop pictures were 21.75 MB as HEIC at the median and 4.32 MB as JPG; the median factor per image was 0.33. On October 19, 2026 on the MacBook Pro, none of them got bigger as a JPG, with factors between 0.12 and 0.44.

So whether an image grows when you convert it depends on the individual HEIC, not just on the format.

How do you convert HEIC to JPG on a Mac?

In Preview with File > Export and the JPEG format, which also works for several images at once (Preview User Guide, checked October 19, 2026), or in Terminal with sips -s format jpeg. At quality 80 (-s formatOptions 80), the 20 screenshots came out 2.49 times as large at the median on the MacBook Pro on October 19, 2026, instead of 2.97 times.

How was this measured?

The measurement covers two groups of HEIC files on October 19, 2026 on a MacBook Pro with M5 Pro running macOS 27.0.1.

  1. Screenshots: 20 captures of a Chrome window with screencapture -x -o -l <window> -t heic, each 4112 × 2580 pixels; 7 of text, 7 of interface, 6 of photo. The same window is used in Is a Mac screenshot smaller as a JPG than as a PNG?.
  2. Desktop pictures: all 17 HEIC files in /System/Library/Desktop Pictures, /System/Library/Wallpapers and the macOS Tahoe pictures, graphics and photos; 15 at 6016 × 6016 pixels, one each at 3840 × 2160 and 4096 × 2160.
  3. Conversion: sips -s format jpeg <HEIC> --out <JPG>, once without a quality setting and once each with -s formatOptions 90 and 80 (options as described in man sips on macOS 27.0.1, checked October 19, 2026).
  4. Analysis: file size in bytes, median and range of the JPG to HEIC factors; 1 KB is 1,000 bytes, 1 MB is 1,000,000 bytes.

HEIC photos from an iPhone and image quality were not measured; the captures themselves are not published.