Compress an image to 3 MB.
Drop your photos and download each one as a JPG under 3 MB. The quality is lowered first and the pixel dimensions only when that is not enough; the photo is never cropped. It runs in your browser; nothing is uploaded.
Under 3 MB per image, saved as JPG
Limits come from each platform's own help pages, summarised in the guides (checked 24 September 2026).
Who asks for 3 MB.
Lines from Herofab's platform guides that name 3 MB, as a limit, a recommendation or one end of a range. Each row links to the guide and its official source.
| Platform | Rule | What the guide says | Read |
|---|---|---|---|
| Miinto | File size | Maximum 3 MB | 11 October 2026 |
| Coupang | File size | 10 MB or less in the seller academy's listing guide; 3 MB or less through the product API | 11 October 2026 |
| Temu | File size | 3 MB or less per image | 12 October 2026 |
| Temu | Size chart image | JPEG, JPG or PNG, at least 800 pixels wide and 800 pixels high, aspect ratio (width to height) of at least 1:3, 3 MB or less | 12 October 2026 |
| Reddit Ads | File size | Maximum 3 MB for an image ad; in a carousel 20 MB per file and 3 MB for GIFs; maximum 10 MB for free-form ad images | 12 October 2026 |
| Reddit Ads | Thumbnail | Recommended landscape 4:3 at 400 × 300 pixels; square 1:1 at 300 × 300 and landscape 16:9 at 400 × 225 pixels are acceptable; maximum file size 3 MB; shown only in conversation placement and compact view | 12 October 2026 |
| SHEIN | File size | 3 MB or less per image | 12 October 2026 |
3 MB in numbers.
Counted as the compressor counts: 1 KB is 1,000 bytes and 1 MB is 1,000,000 bytes. Bits per pixel divides the limit in bits by the pixels of a 12-megapixel phone photo (4,032 × 3,024 px) kept at full size; the uncompressed size counts 3 bytes per pixel.
- Bytes
- 3,000,000
- Bits
- 24,000,000
- Pixels in a 12-megapixel phone photo
- 4,032 × 3,024 = 12,192,768
- Bits per pixel at full size
- 24,000,000 ÷ 12,192,768 = 1.97
- Uncompressed, 3 bytes per pixel
- 36,578,304 bytes, 12.2 times the limit
Other limits.
3 MB, answered.
Which platforms ask for 3 MB?
Miinto, Coupang, Temu, Reddit Ads, and SHEIN. The table on this page gives each rule in full and links to the platform's guide.
How many bytes is 3 MB?
3,000,000 bytes: the compressor counts 1 MB as 1,000,000 bytes, the stricter of the two common readings. Counted in units of 1,024, 3 MB would be 3,145,728 bytes, so a file under 3,000,000 bytes is under the limit on either count.
How many bits per pixel does 3 MB leave for a 12-megapixel photo?
1.97, if the photo keeps all 12,192,768 pixels (4,032 × 3,024): 24,000,000 bits divided by 12,192,768. Uncompressed, at 3 bytes per pixel, the photo is 36,578,304 bytes, 12.2 times the limit. The compressor lowers the JPG quality first and reduces the pixel dimensions only when that is not enough.
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