What size should a watermark be?

We suggest 15 to 25% of the photo width for a logo or short name, and more for long text. In our measurements on an iPhone 18 Pro, a photo shown across the full screen is 66.6 mm wide, so a mark 20% of the image width is 13.3 mm wide.

Published October 30, 2026. Drafted with AI assistance and checked against the sources linked on this page. How we write our guides.

Watermark size as a share of the photo width

Our tool sizes a mark as a share of the photo width, so the same setting gives the same proportions on a 1,000-pixel photo and a 6,000-pixel one. The useful question is how big that share is on the screen where people will see it. We worked it out for four current phones from the makers' own pixel counts and pixel densities: the iPhone 18 Pro and 18 Pro Max (Apple states 2622 by 1206 pixels and 2868 by 1320 pixels, both at 460 ppi) and the Pixel 11 Pro and Pro XL (Google states 495 PPI and 486 PPI).

A photo shown across the full screen width is 66.6 mm wide on an iPhone 18 Pro. Across the four phones it is between 65.7 mm and 72.9 mm. The table gives the width of the mark itself, by share of the image width.

If an app shows the photo narrower than the full screen width, the real mark is smaller than these figures. We did not measure any app.

The share is what you set in our tool. Its Size (% of image width) control runs from 1 to 100 and starts at 25, and the mark's whole width, the text box or the logo, is that share of the image width. In the photo watermark tool you can try a share and look at the preview before you save.

Text height that stays readable

For a text mark the width is not the number that matters; the height of the letters is. Longer text set to the same width has smaller letters. In our measurements, a one-line text mark set to 10% of the image width has a capital-letter height of 0.85 mm for 10 characters, 0.57 mm for 15 and 0.42 mm for 20 on an iPhone 18 Pro. At 20% of the width the heights are 1.7 mm, 1.13 mm and 0.85 mm.

As a share of the image width, the letter height is the same on every phone: about 2.5% of the width for 10 characters at 20% wide, and about 1.3% for 20 characters at 20% wide. We found no standard that sets a legible minimum for a watermark. As an illustration only, if you want capital letters 1.5 mm tall on an iPhone 18 Pro, a 20-character mark must be about 35% of the image width and a 10-character mark about 18%.

From that we suggest, as our own advice and not a rule from any platform: keep the text short, and use 15 to 25% of the width for a logo or a short name. If the text has to be long, either make the mark wider or put the name on two lines.

Watermark size in Lightroom

The two Lightroom apps size a mark differently, and neither page gives a recommended number.

In Lightroom Classic, the Watermark Editor has a Size effect with three modes. Adobe says Proportional scales the watermark larger or smaller, Fit sizes it across the width of the photo, and Fill sizes it to fill the height and width of the photo. The editor opens from Edit > Edit Watermarks on Windows or Lightroom Classic > Edit Watermarks on macOS (Adobe). The same page advises that if you have trouble seeing the watermark on final images, you should experiment with a larger size or a different position.

In Lightroom desktop, a text watermark is sized with a Size slider that Adobe describes as a font size, so it is not a share of the photo. A graphical watermark has its own size setting (Adobe). More on both apps is in our guide to a watermark in Lightroom.

Watermark size in Photoshop

This is our arithmetic, not an Adobe setting. If you place the mark yourself, work out its width in pixels from the share: on a photo 4,000 pixels wide, 20% is 800 pixels and 25% is 1,000 pixels. Then scale the mark to that width and use the same percentage on every photo of the batch.

Watermark size on YouTube

YouTube's published rule is a minimum for the image file you upload, not a share of the video. In YouTube Studio on a computer, Google's page for managing your channel branding says the video watermark must be at least 150 by 150 pixels and under 1 MB, and the image must be 1:1. Its steps say to change the size of your image, then click DONE (YouTube Help). The page gives no on-screen size, so we cannot say how large it shows on a viewer's screen. The step-by-step and the display options are in our guide to a YouTube watermark.

Where the mark sits also matters

A mark that is the right size can still be cut off. In our crop data, with a mark 20% of the width and 3% in from the edge, a photo at the 3:2 ratio loses a corner mark entirely in three of five common centre crops (4:5, 3:4 and 9:16), so see where to put a watermark on a photo, and judge how strong the mark should look with our guide to watermark opacity.

How we measured

We took the pixel size and pixel density each maker states for the four phones. Screen width in millimetres is the short side in pixels divided by the pixel density, times 25.4. A mark's width is its share times that screen width. As a check, our pixels and densities give diagonals of 6.27 and 6.86 inches for the iPhones, which are the figures Apple states for the standard rectangle, and 6.32 and 6.75 inches for the Pixels, against the 6.3 and 6.8 inches Google states.

For the letter height we assumed an average character width of 0.55 em and a capital height of 0.7 em, so the height of a one-line mark is its width times 0.7, divided by the number of characters times 0.55. Real typefaces differ, and all-capital text is wider than average, which would make the letters smaller than shown. We did not test tablets, foldables, display zoom, viewing distance or the margins an app puts around a photo. We left out the Galaxy S26 Ultra because we could not read a pixel size and density from Samsung's own pages as text.

Sources

Checked October 30, 2026.

• www.apple.com/iphone-18-pro/specs
• store.google.com/us/product/pixel_11_pro_specs
• helpx.adobe.com/lightroom-classic/desktop/workspace/using-watermark-editor.html
• helpx.adobe.com/lightroom/desktop/save-share-and-export/save-share-photos.html
• support.google.com/youtube/answer/10456525