Working out watermark coordinates as ratios
Pinning a watermark in px means redoing the position and the size every time the image dimensions change. Setting the width and the margin as shares of the image keeps the same proportion at any resolution. Enter the dimensions and the shares and the coordinates for all nine spots appear at once, along with CSS for the one you select.
How it is calculated
Watermark width = image width x width share, height = width divided by the aspect ratio, and margin = shorter side x margin share. The left coordinate is the margin, the center is (image width - watermark width) / 2 and the right is image width - watermark width - margin, with the vertical axis following the same pattern. The rule-of-thirds lines at one third and two thirds of each side are listed as well.
Limits
As of October 2026 there is no official standard for watermark placement, size or opacity, so this tool proposes no values and does not judge which spot is better. The position of the subject, legibility against a bright background and thumbnails cropped to other ratios are not modeled, so check the result on the real image.
Frequently Asked Questions
There is no official recommended spot. It depends on where the subject sits, so this tool calculates the coordinates for all nine positions and leaves the choice to you.
No. There is no official standard for watermark opacity either, so none is proposed. This tool calculates size and coordinates only.
A centered position is the middle of the image minus half the watermark, so the margin plays no part. The margin applies only to the corners and the edge midpoints.