Download 4 MB JPG image for testing
Preview the image and test your image-upload limit. The preset is 4 MiB (4,194,304 bytes); choose MB for decimal megabytes.
1 MB = 1,000,000 B · 1 MiB = 1,048,576 B
Advanced: test an upload limit
Enter the byte limit above, then choose one byte below, the exact limit or one byte above. Each choice uses the same base: 4,194,304 B. Generate and download each file to test your endpoint.
Where a 4 MB JPG comes up
- Finding the largest photo your serverless upload route can take before you move uploads to presigned URLs.
- Testing client-side resizing that should only start above 4 MB.
- Checking mobile upload progress bars with a file that takes a few seconds on 3G-like speeds.
Limits it lands on
- As base64 it becomes about 5.59 million bytes, which still fits AWS Lambda's 6 MB synchronous payload; the 5 MB JPG does not.
- Vercel Functions accept request bodies up to 4.5 MB, so this image, including the multipart overhead, still fits.
- Over PHP's default 2M upload_max_filesize and Django's 2.5 MB in-memory threshold.
What is inside the file
About 64 comment segments of up to 65,533 bytes each fill the space between the start-of-image marker and the encoded 800 × 600 picture.
The exact byte count is 4 × 1,048,576 = 4,194,304, which is identical on every download.
Questions
Why does 4 MB work on Lambda while 5 MB fails?
Binary uploads pass through API Gateway as base64, adding about one third: 4 MiB becomes about 5.6 million bytes and 5 MiB about 7 million, over the 6 MB limit.
Is 4 MB a realistic phone photo size?
Yes; many compressed smartphone photos are a few megabytes, which makes this a sensible test case for an upload route.
Reference and checks
Format reference: ITU-T T.81 (JPEG).
Preset target: 4 MiB (4,194,304 bytes). Verify the downloaded file's byte count.
Generate another size in this format · Technical notes for every format · Guide to testing file upload limits · Data processing and privacy
Related tools: Image Convert · Resize Image · Compress Image.
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