i have a problem with illustrator when i finish my t shirt design 4500x5400px and export it as a png
the image i get is so big 18750x22500px... i dont know aht to do please help me
Make sure your document DPI and the export DPI match.
You should export it at 72 ppi instead of 300 ppi, which makes Illustrator create more pixels.
amazon suggest to export the design at 300 ppi not 72
Amazon doesn't understand resolution.
They can either give you a physical size and then a resolution to accompany it. Those two combined will lead to pixel dimensions (that's just math).
Or they can give you the pixel dimensions directly.
If you want to keep the amount of pixels but change the resolution without changing the amount of pixels, just go in Photoshop to Image > Image Size... and set the Resolution to 300 Pixels/Inch and Uncheck Resample. Save the file.
On a Mac you can also change the resolution without resampling with the Preview app with Tools > Adjust Size...