Uploading straight from the camera at full resolution, then wondering why an Etsy or Walmart upload fails on a one megabyte cap.
Compression
File size
Also called image file size, kb mb or photo size. Here is what it means, when it changes what you export, and what people get wrong.
CompressionRuns on your deviceUpdated 10 August 2026
The short answer
File size is how many bytes an image takes up on disk, usually measured in KB or MB. It is driven by pixel count, format, quality setting, bit depth and how much fine detail the picture contains. Resizing the pixel dimensions almost always cuts more bytes than compressing harder.
Updated
The short version
File size at a glance
| Quick fact | Detail |
|---|---|
| Biggest lever | Pixel dimensions, not the quality slider |
| Scaling | Doubling width and height roughly quadruples pixels |
| Tightest common cap | 1 MB, on Etsy and Walmart Marketplace |
| Hidden weight | EXIF, ICC profiles, embedded thumbnails |
| Format matters | PNG photos are far larger than JPEG or WebP |
Slide the table sideways to see every column.
What actually drives the byte count?
- Pixel count: the dominant factor. Doubling both width and height quadruples the number of pixels, and roughly quadruples the size before compression.
- Format and mode: a lossy JPEG, WebP or AVIF of a photograph is far smaller than a lossless PNG of the same picture. On flat graphics the ranking reverses.
- Quality setting: how aggressively the encoder quantises detail away.
- Bit depth and channels: 16 bits per channel doubles the raw data against 8 bits, and an alpha channel adds a fourth channel to store.
- Image complexity: fine texture, noise and busy detail all resist compression. A flat white background costs almost nothing.
- Metadata: EXIF, embedded ICC profiles, embedded preview thumbnails and editor history can add hundreds of kilobytes to an otherwise small file.
Why is resizing a better lever than compressing harder?
Because the two do different kinds of damage. Halving an image's width and height removes three quarters of its pixels, and at the smaller display size nobody can tell, because the detail you deleted was never visible there anyway. Dropping the quality setting by the equivalent amount leaves the pixel count untouched and instead introduces blocking, ringing and colour bleed that are visible at any size.
So work in this order. Decide the largest size the image will genuinely be displayed or zoomed at, resize to that, then choose a quality setting, then strip metadata if you still need bytes. A 6000 pixel camera file exported at high quality will be enormous, and resizing it to the 2000 pixels a marketplace actually shows will do more than any slider.
What file size limits do marketplaces enforce?
Caps vary widely, and some are far tighter than sellers expect. These are the published limits for the platforms that state one.
| Platform | File size limit | Dimension guidance |
|---|---|---|
| Etsy | Files over 1 MB may fail to upload | At least 2000 px on both width and height; first photo at least 635 px wide |
| Walmart Marketplace | Maximum 1 MB per file | Recommended 2000 x 2000 px at 300 ppi for zoom |
| Meta and Instagram Shop catalog | Maximum 8 MB | Minimum 500 x 500 px, recommended 1024 x 1024 px square |
| eBay | Up to 12 MB per file | Minimum 500 x 500 px, recommended about 1600 x 1600 px |
| Shopify | Under 20 MB | Up to 5000 x 5000 px or 25 MP; 2048 x 2048 px displays best for square product images |
Etsy and Walmart are the two that catch people out, because both want large pixel dimensions and both cap the file at around a megabyte. That combination forces you to compress rather than upload a straight camera export.
How do you get a stubborn file under a hard cap?
Work through it in this order and stop as soon as you are under.
- Resize to the dimensions the platform actually asks for, no larger.
- Strip EXIF, embedded thumbnails and any ICC profile the destination does not need, keeping sRGB tagging if colour accuracy matters.
- Switch a photograph off PNG. A plain-background product shot saved as PNG is often several times larger than the same picture as a good JPEG or WebP.
- Lower the quality setting in small steps, checking edges and flat backgrounds each time.
- Flatten transparency if the destination does not support it. Etsy in particular does not support transparent PNGs, and transparent areas appear black.
A batch editor makes this repeatable across a whole listing set, which is what Photomop's resize and compression tools are built to do in one pass.
What people get wrong about file size
Each one is a real failure mode, not a style preference.
Saving a plain-background product photo as PNG, which can be several times the size of an equivalent JPEG.
Compressing hard to hit a cap while leaving the image at 6000 pixels wide, so the result is both damaged and oversized.
Assuming a smaller file always means faster pages, when serving one correctly sized image beats aggressively squashing an oversized one.
Questions people ask
File size, answered
The follow-up questions people search for once they have the definition.
How do I make an image under 1 MB without it looking bad?
Resize first to the dimensions the platform needs, strip metadata, then export as JPEG or WebP somewhere in the low to mid eighties. For most product photography that lands well under a megabyte with no visible damage at normal viewing size.
Why is my PNG so much bigger than my JPEG?
PNG is lossless, so it stores every pixel exactly. Photographs contain vast amounts of fine variation with little repetition for lossless compression to exploit. JPEG discards detail your eye will not miss, which is why it wins heavily on photographic content.
Does file size affect how images rank or load?
It affects loading, which affects the page speed metrics search engines measure. It has no direct bearing on image quality scores on marketplaces. The practical goal is the smallest file that still looks correct at the size customers view it.
Is KB or MB the right unit for a listing photo?
Most well prepared listing photos land in the low hundreds of kilobytes. Anything running into several megabytes is usually oversized in pixels, saved as PNG when it should be JPEG, or carrying an embedded preview and metadata it does not need.
Same cluster
More from the glossary
Neighbouring entries, so every term in the set is one hop from every other.
From the studio
Tools that do this
Each one runs on your own device, so the photo stays where it is.
Sources
Where the facts on this page come from. Every link opens the specification, standard or documentation the claim was read at.
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Photomop is a photo studio that runs on your own device. Resize, crop, compress, convert, batch edit, remove a background and change one all work in the browser tab you are reading this in, at full resolution and with no watermark. The on-device page shows you how to check that the photo stays put.