If you try to upload your artwork and see "Image file is too large. Maximum size is 150 MB.", your file is over Printumo's upload limit. This is one of the most common questions we get, and the good news is that it is almost always easy to fix. A smaller file does not mean a worse print. In most cases you can get far below the limit and lose nothing that would ever be visible on the finished print.
The upload limits
Printumo accepts these files when you create a product:
JPEG (.jpg, .jpeg): up to 150 MB
PNG (.png): up to 150 MB
TIFF (.tif, .tiff): up to 150 MB
PDF (.pdf): up to 100 MB
There is also a limit on the number of pixels: 320 megapixels, which is roughly 17,900 x 17,900 pixels. That is far more than any of our print sizes needs.
The messages you may see are:
"Image file is too large. Maximum size is 150 MB." Your JPEG, PNG or TIFF is over 150 MB.
"PDF file is too large. Maximum size is 100 MB." Your PDF is over 100 MB.
"Uploaded image is too large. Maximum supported resolution is 320MP" The file has too many pixels. This message appears after the upload finishes, because we count the pixels once the file has arrived.
Why a bigger file does not mean a better print
This is the part that worries most sellers, so it is worth being precise.
Print sharpness is decided by how many pixels you have across the printed size, measured in DPI (dots per inch). It is not decided by megabytes. Two files can have exactly the same pixel dimensions and print exactly the same, while one is 30 MB and the other is 400 MB. The extra megabytes are layers, 16-bit colour depth and uncompressed data. None of that reaches the paper.
Printumo always builds the print file itself from your upload:
Fine art paper prints are produced at 300 DPI at the ordered size.
Canvas prints are produced at 150 DPI at the ordered size, plus the wrap around the edges.
If your file has more pixels than that, we scale it down. Pixels above the target do not improve the print, and megabytes above the target only make the upload fail.
The pixel dimensions you actually need
The formula is: pixels = (centimetres ÷ 2.54) × DPI. Use 300 DPI for fine art paper and 150 DPI for canvas.
Fine art paper at 300 DPI
30 x 40 cm: 3,543 x 4,724 pixels
50 x 70 cm: 5,906 x 8,268 pixels
70 x 100 cm: 8,268 x 11,811 pixels
100 x 140 cm: 11,811 x 16,535 pixels
Canvas at 150 DPI
30 x 40 cm: 1,772 x 2,362 pixels
50 x 70 cm: 2,953 x 4,134 pixels
70 x 100 cm: 4,134 x 5,906 pixels
100 x 140 cm: 5,906 x 8,268 pixels
A JPEG at these dimensions sits comfortably inside the 150 MB limit, even at our largest size and the highest quality setting.
After you upload, every size in the product editor shows a coloured quality dot. Green means good or great, amber means average, and red means the file is too small for that size. Use the dots to check your file before you launch the product.
Why your file is so large
A file of several hundred megabytes is almost always one of these:
An uncompressed TIFF or a layered PSD. These store every pixel in full, and every layer on top of that.
16 bits per channel instead of 8. This doubles the size and makes no visible difference in print.
An export at 600 DPI. That is four times as many pixels as 300 DPI, and we scale them straight back down.
Layers, masks, smart objects or saved history. None of this is used for printing.
How to make the file smaller without losing quality
The goal is to keep the pixel dimensions and change everything else. Do these four things:
Flatten the image, so it has no layers.
Convert it to 8 bits per channel.
Convert the colour profile to sRGB.
Save it as a JPEG at a high quality setting.
A high quality JPEG is not a compromise. The print files we send to our print partners are JPEG files, and at quality 90 or above the difference is not visible in print.
In Adobe Photoshop
Open Image > Mode and choose 8 Bits/Channel.
Open Layer > Flatten Image.
Open Edit > Convert to Profile and choose sRGB IEC61966-2.1.
Open Image > Image Size and check the pixel dimensions against the list above.
Choose File > Save a Copy, select JPEG, and set the quality to 10 or higher.
In Affinity Photo
Choose Document > Convert Format / ICC Profile and select sRGB with 8 bits per channel.
Choose Document > Resize Document and check the pixel dimensions.
Choose File > Export, select JPEG, and set the quality to 90 or higher.
In GIMP (free)
Choose Image > Flatten Image.
Choose Image > Precision and select 8-bit integer.
Choose File > Export As, give the file a .jpg ending, and set the quality to 90 or higher.
On a Mac, without design software
Open the file in Preview.
Choose File > Export.
Set the format to JPEG and move the quality slider close to Best.
In a browser, without installing anything
Photopea (photopea.com) is a free browser tool that works much like Photoshop. It opens your file in the browser, and you can then use File > Export as > JPG with the quality set to 90 or higher.
If the file is still too large
If a flattened 8-bit JPEG is still over the limit, your file has more pixels than any of our sizes can use. Reduce the pixel dimensions to the numbers listed above for the largest size you plan to sell, then export again. For fine art paper, anything from 200 DPI upwards still prints well, so you have room to go below 300 DPI if you need it.
What not to do
Do not use a "compress my image" website without checking the result. Many of them cut the pixel dimensions as well as the file size, and that does damage the print.
Do not upscale a small file to reach the pixel numbers above. Adding pixels that were never captured makes the print softer, not sharper.
Do not upload a screenshot or a copy downloaded from social media. Always start from your original artwork.
Do not send a ZIP file. The product editor cannot open it.
A worked example: a 338 MB file for a 100 x 140 cm print
This is a real case from our support inbox. The seller had a 338 MB file and wanted a 100 x 140 cm fine art paper print.
A 100 x 140 cm paper print needs 11,811 x 16,535 pixels at 300 DPI.
An uncompressed 8-bit TIFF at those dimensions is around 580 MB, and a compressed one lands in the few hundred megabyte range. That is why the file was so large.
Flattened, converted to 8 bits and sRGB, and saved as a JPEG at quality 10, the same artwork keeps all 11,811 x 16,535 pixels.
The file then uploads without trouble and prints at the full 300 DPI.
Nothing was lost. The print file we send to the print partner would have been a JPEG at exactly those pixel dimensions anyway.
A note on PDF and TIFF uploads
When you upload a PDF or a TIFF, Printumo converts it to a high quality JPEG during the upload, and that JPEG becomes the file we print from. Two things follow from this:
Only the first page of a PDF or a multi-page TIFF is used.
The converted file is capped at 17,000 pixels on the long edge. That is enough for our largest print size, but a bigger source file will be reduced.
If you want full control over the conversion, export the JPEG yourself before you upload it.
Still stuck?
Send us a message with the print size you want and, if you can, the file itself. We will check the resolution and tell you exactly what to change before you launch the product.