Download 20 MB PNG file for testing
Preview the PNG and check its size in your upload form. The preset is 20 MiB (20,971,520 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: 20,971,520 B. Generate and download each file to test your endpoint.
Where a 20 MB PNG comes up
- Testing Shopify or other e-commerce image limits with a lossless file.
- Checking image resizing services that must decode the whole bitmap.
- Measuring memory use in thumbnail pipelines with a large lossless image.
Limits it lands on
- Shopify accepts images up to 20 MB and 20 megapixels; this PNG is at the file-size limit with about 7 megapixels.
- Telegram bots can download it with getFile, whose ceiling is 20 MB.
What is inside the file
Unlike the JPGs here, this PNG is not padded with comments: the generator picks the dimensions (2560 × 2730, 8-bit truecolour) so the stored pixel rows fill 20,969,130 bytes, and a short text chunk makes up the remainder.
Pixel data is written in uncompressed deflate blocks, so decoders do real work — about 21 MB of RGB values.
Questions
Why is this PNG so large?
The pixels are stored without compression, so the file size reflects the true bitmap size of a 2560 × 2730 image.
Will re-saving shrink it?
Yes. Any PNG optimiser will compress the pixel data and the file will become much smaller.
Reference and checks
Format reference: W3C PNG specification.
Preset target: 20 MiB (20,971,520 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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