Why is my JPEG too large — and how to shrink it on Mac

You exported a JPEG and it’s 8 MB. You expected JPEG to be small — that’s the whole point of the format. So what gives? The short answer: your source is huge and the encoder is using its quietest setting.

Why this happens

Three things stack up to make a JPEG enormous:

• Quality setting near 100. iPhones, Sony cameras, and most DSLRs default to quality 95-98 for JPEG. The visual difference between 95 and 80 is essentially zero. The file-size difference is roughly 2x.
• Pixel count. A 48 MP iPhone JPEG is 8000x6000 pixels. That’s a lot of bytes even efficiently compressed.
• EXIF and embedded thumbnails. Modern cameras embed a thumbnail, a colour profile, GPS data, and a long history of edit metadata. Easily 100-500 KB of overhead.

The native way

Preview lets you fix all three at once. Open the JPEG, then:

1. Tools → Adjust Size. Drop the longest edge to 2000-2400px.
2. File → Export. Pick JPEG. Drag Quality to about 80%. Watch the size estimate.
3. Save the new copy.

For Terminal users, sips does the same job in one line:

sips -s format jpeg -s formatOptions 80 -Z 2000 huge.jpg —out smaller.jpg

That alone takes a 12 MB iPhone JPEG down to 600-900 KB.

The faster way

When you have more than one — or you want the EXIF stripped too — Download Melt does the lot in one pass.

1. Download Melt and open it.
2. Drag your JPEGs in.
3. Pick quality 80 and optionally cap the longest edge at 2000px.
4. Click Compress. EXIF is stripped automatically.

The EXIF strip is the part most people forget. Your JPEG has location coordinates, camera serial number, and edit history baked in — none of which need to follow a photo onto the public internet.

How much smaller will it really get?

The math compounds. A 12 MB JPEG, processed by Melt at quality 80 with a 2000px cap:

• Resize alone (no quality change): ~30% of original = 3.6 MB.
• Quality 80 at original size: ~50% of original = 6 MB.
• Both together: ~7-10% of original = around 800 KB.

The real reason JPEGs are too large isn’t usually the compression — it’s that nobody bothered to resize. A 2000px-wide photo is more than enough for everything except print. Anything more is just bytes you’re paying to transmit.