A 10 MB PNG test file

About this file

A 10 MB test file in PNG format, sized to exactly 10,485,760 bytes. Free to download with no signup, for verifying upload limits and file-handling behaviour.

The MD5, SHA-1 and SHA-256 values listed above are the real digests of this file. Recomputing them after download confirms the transfer was not corrupted, and they double as known-good expected values when testing a hashing library.

What this size means in practice

10 MB is one of the most common "round number" caps chosen for forms and CMS uploads. It is exactly 10,485,760 bytes (10 × 1024 × 1024), which also lets you detect whether an implementation computes MB with 1000 or with 1024.

An implementation using 1000 rejects anything past 10,000,000 bytes, so this file fails there. One using 1024 accepts it as exactly at the limit. To pin down the boundary precisely, combine it with the threshold set (9.9 MB / 10.0 MB / 10.1 MB).

Getting a feel for this size

On a 10 Mbps link the transfer takes roughly 8.4 seconds, and about 839 ms at 100 Mbps. Base64-encoded it grows to roughly 13,653 KB.

Estimating a photographic PNG at roughly 2 bytes per pixel, this size works out to around 5,242,880 pixels — about 2,644 × 1,983 px at a 4:3 aspect ratio. Compression varies enormously with image content, so treat this purely as an order-of-magnitude figure.

What to check for this format

PNG is lossless and carries an alpha channel. Every file starts with the fixed 8-byte signature 89 50 4E 47 0D 0A 1A 0A, followed by IHDR / IDAT / IEND chunks. The key question for upload validation is whether your code identifies the file by those leading bytes rather than by its extension.

• Whether the alpha channel survives resize and conversion — converting to JPEG destroys it
• Whether image libraries such as GD, ImageMagick, or sharp hit their memory ceiling — PNG memory use scales with decoded pixel count, not file size
• Whether metadata such as tEXt chunks is stripped — PNG has no EXIF, but text chunks can retain information