Upload errors are often caused by confusing file size with image dimensions. File size is measured in KB or MB, while dimensions are measured in pixels such as 1920 × 1080.
Check width and height
Use the TheTecTricks Image Dimension Checker to select a local image. The tool reads its width and height in the browser and also shows the file size and aspect ratio.
Compare with the destination requirements
If a website asks for a minimum width, your image must meet that pixel requirement even if its file size is small. If it asks for a maximum file size, compression may be needed after the dimensions are correct.
Watch the aspect ratio
An aspect ratio describes the shape of an image. Resizing both dimensions independently can stretch the picture, so preserve the ratio unless the destination specifically needs a different shape.