Every stock agency publishes a minimum image size, and no two of them measure it the same way. Adobe Stock counts megapixels. Shutterstock counts megapixels but caps file size on a separate axis. Alamy skips megapixels entirely and asks for uncompressed megabytes. A file that clears one review can be bounced by another before a human ever opens it.
That inconsistency is the actual problem for anyone who shoots once and distributes everywhere. The useful question is not what a single agency wants — it is which export clears all of them at the same time. Below are the current requirements, taken from each agency's own contributor documentation rather than from third-party guides.
Three agencies, three different units
Here is the same requirement expressed three ways:
- Adobe Stock — 4MP to 100MP, JPEG in sRGB, maximum 45MB per file.
- Shutterstock — at least 4MP, JPEG or unlayered TIFF, 50MB via the browser uploader.
- Alamy — over 17MB when uncompressed, saved as a JPEG at quality level 8 or above.
Two of those are dimension rules and one is a data-volume rule, which is why contributors regularly pass Adobe and fail Alamy with the identical file. Megapixels describe how many pixels an image contains. Uncompressed size describes how much memory those pixels occupy once the JPEG is decoded. They move together, but the thresholds do not line up.
Adobe Stock: 4MP to 100MP, with a ceiling as well as a floor
Adobe's photo submission requirements set a resolution band of 4MP to 100MP, a maximum file size of 45MB, JPEG format with an sRGB colour profile, and content free of watermarks, timestamps or branding. The upper bound is the part most guides leave out. A modern 60MP or 100MP body exporting at maximum JPEG quality can push past 45MB long before it approaches the megapixel ceiling, and the upload simply fails.
Adobe also notes that larger files give customers more flexibility, and advises resizing accurately so detail survives. That is a quality argument rather than an earnings promise — no agency pays per pixel. The practical reading is that you should not deliberately downsize a good file to be safe, but you also gain nothing from exporting at a size that risks the 45MB wall.
Resolution failures are the cheapest kind to fix because they happen at upload rather than in review. The expensive rejections are the subjective ones — focus, noise, similarity — which we cover separately in Adobe Stock rejection reasons.
Shutterstock: 4MP, and the trap hidden in the EPS rule
Shutterstock's technical requirements for images put the floor at 4MP and are unusually explicit about the difference between megapixels and megabytes, presumably because the confusion generates so many support tickets. Megapixels are width multiplied by height. Nothing about the saved file size enters into it.
Their own worked examples make the point better than any explanation. An image at 2000 x 2400 pixels is 4.8MP and passes. An image at 1200 x 3000 pixels is 3.6MP and is rejected by the system — even though its long edge is considerably greater. Shape matters more than most contributors expect, and tall crops from a moderate sensor fail this check surprisingly often.
The file size limits sit on a separate track and depend on how you deliver. Through the browser you get 50MB for photos and 100MB for EPS. Over FTPS the ceilings change: JPEGs still cap at 50MB, EPS at 100MB, but TIFFs are allowed up to 4GB. If you work with large layered originals, that FTPS allowance is the only route that will take them — after you flatten, because layered TIFFs and PSD files are not accepted.
Vector contributors have their own version of the trap. EPS files must fall between 4MP and 25MP, and that measurement is taken from the bounding box around the artwork rather than the artboard. An artboard comfortably above 4MP with a small graphic sitting inside it will still throw an error, because the bounding box hugs the artwork itself. The fix is to scale the artwork up in the Transform panel and then resize the artboard to match, not the other way round.
One more line in that document is worth reading twice: still frames pulled from video are generally not accepted, even from 8K footage, because they do not meet the technical quality standard. Resolution alone does not rescue a frame grab. If you shoot video and stills for the same scene, they remain two separate submissions with two separate quality bars.
Alamy measures uncompressed megabytes, not megapixels
Alamy's uploading guidance asks for a file over 17MB when uncompressed, and notes that such a file usually lands somewhere around 3MB to 5MB once saved as a JPEG. They also want quality level 8 or above, baseline standard, RGB. The uncompressed figure is what Photoshop shows you when the image is open, not what the finder or explorer reports.
You can convert that threshold into familiar units. An 8-bit RGB image occupies three bytes per pixel once decoded, so 17MB of uncompressed data corresponds to roughly 5.9 million pixels — call it 6MP. That is why Alamy quietly sits above both Adobe and Shutterstock: a clean 4.8MP file that satisfies Shutterstock's example is comfortably under Alamy's bar. Anyone distributing to all three needs to plan around the 6MP figure, not the 4MP one.
Two Alamy policies sit outside the size question but change what is worth uploading there at all. They accept images from mirrorless and DSLR cameras, plus most mainstream smartphones released in 2020 or later. And they do not accept AI-generated images, which they have set out as a deliberate editorial position rather than a temporary restriction. A portfolio built primarily on generative work has nowhere to go on Alamy regardless of how large the files are.
Stock video is a fixed list, not a minimum
Photo requirements describe a range. Video requirements describe a menu. Adobe's video submission requirements name the accepted horizontal resolutions outright: 1920x1080, 2048x1080, 3840x2160, 4096x2160 and 4096x2304. Clips must be delivered at their native frame size, and up-converting HD footage to 4K is explicitly called out as something not to do.
Vertical and square clips have their own lists. Vertical is accepted at 1080x1920, 2160x3840, 2160x4096 and 2304x4096, and Adobe asks that it be shot natively at 9:16 rather than converted from a horizontal original. Square runs at 1080x1080 or 2160x2160. If vertical is a growing part of your output, the format and demand side is worth reading alongside the specs — we went through it in what vertical video is and why stock buyers want it.
The surrounding constraints matter as much as the pixel dimensions. Clips run 5 to 60 seconds with a 3.9GB file ceiling. Frame rates must be standard values — 23.98, 24, 25, 29.97, 30, 50, 59.94 or 60 — and should not be converted from the native rate unless the clip is deliberately slow or fast motion. Containers are MOV, MPG or MP4, with ProRes and H.264 the recommended codecs, and audio at 48 kHz, 16-bit uncompressed. Video generated with AI carries an additional floor of 1080 pixels on both sides.
The export window that clears all three
Stack the constraints and a single window appears. The floor is set by Alamy at roughly 6MP. The ceilings are set by Adobe at 100MP and 45MB. Shutterstock's browser limit of 50MB is more generous than Adobe's 45MB, so Adobe governs the top end. That leaves an export target of somewhere between 6MP and 100MP, saved as a JPEG in sRGB, kept under 45MB.
In practice that is not a difficult window to hit. Almost any full-frame or APS-C camera made in the last decade produces files well above 6MP, and a quality setting of 10 to 12 in most editors keeps a 24MP export in the 8MB to 20MB range — far from the 45MB wall. The contributors who run into trouble are usually at one of the two extremes: heavy croppers pushing files below 6MP, and high-megapixel shooters exporting at maximum quality without checking the resulting size.
The recommendation that follows is to build one master export per image rather than per-agency variants. Variants multiply storage, multiply the chance of sending the wrong version, and gain nothing when a single file already satisfies every threshold. Keep the exceptions narrow: vectors need their own EPS treatment, and video is delivered at its native frame size regardless. If you are moving volume, delivering that master over FTP rather than a browser uploader is the other change worth making — the FTP upload walkthrough covers the setup.
Specs are the easy part of multi-agency delivery
Once the export window is settled it rarely changes. Agencies adjust these numbers every few years at most, and a preset handles it. What changes on every single upload is everything wrapped around the pixels: title length limits that differ by platform, keyword counts that differ again, category systems that share no common vocabulary, release requirements, and a separate FTP endpoint per destination. That is where the hours actually go.
Rastock.ai was built for that second problem. It generates titles, descriptions and keywords once, then delivers to 10+ agencies over FTP and SFTP with per-agency rules applied on the way out — banned and mandatory keyword lists, policy-shaped tags, and rollback if a batch goes wrong. Upload status is tracked per destination rather than guessed at. The feature breakdown goes through the delivery side in detail, and the pricing page lists what each tier covers.
Three things stay off the table by design: there is no revenue share, no claim on your files, and IPTC or CSV export is always available so your metadata can leave with you. There is a 14-day free trial and it does not ask for a card, which is enough time to run a real batch through and compare the output against what you would have written yourself.
Frequently asked questions
What is the minimum resolution for stock photos?
Adobe Stock and Shutterstock both set the floor at 4 megapixels. Alamy uses a different measure entirely — over 17MB uncompressed, which works out to roughly 6 megapixels for an 8-bit RGB image. If you distribute to all three, plan around the 6MP figure rather than 4MP, because a file that satisfies Shutterstock's own 4.8MP example still falls short at Alamy.
Are megapixels the same thing as megabytes?
No, and the two limits are enforced separately. Megapixels are the image dimensions multiplied together: 2000 x 2400 pixels is 4.8MP. Megabytes measure how much storage the saved file occupies. Adobe Stock caps files at 45MB while requiring 4MP to 100MP of resolution, so it is possible to satisfy one limit and breach the other with the same image.
Can I upscale a small photo to meet the minimum size?
You can, but it usually converts a technical failure into a quality failure. Agencies review sharpness and artefacts after the file passes the automated size check, and interpolated detail tends to be visible at review resolution. Adobe advises resizing accurately to maintain clarity, and Shutterstock declines video still frames on quality grounds even at 8K, which signals how that judgement runs.
Do larger files earn more money?
There is no direct link. No major agency pays per pixel, and royalties are set by licence type and subscription terms rather than file dimensions. Adobe does note that larger files give customers more flexibility, which is a discoverability and usefulness argument. The practical position is to submit at your native size within the limits, and not to upscale in pursuit of earnings.
What resolution does stock video need?
Adobe Stock accepts a fixed list rather than a minimum. Horizontal clips must be 1920x1080, 2048x1080, 3840x2160, 4096x2160 or 4096x2304. Vertical is 1080x1920, 2160x3840, 2160x4096 or 2304x4096, and square is 1080x1080 or 2160x2160. Clips run 5 to 60 seconds at standard frame rates, and upscaling HD footage to 4K is explicitly discouraged.
Do I need a different export for each agency?
For ordinary JPEG photography, no. A single master export between roughly 6MP and 100MP, in sRGB, kept under 45MB, satisfies Adobe Stock, Shutterstock and Alamy at once. The exceptions are vectors, where Shutterstock measures 4MP to 25MP on the artwork bounding box, and video, which must be delivered at its native frame size from the accepted resolution list.