Alt text follows a rule that no model knows better than you do: describe what the image communicates, not everything it contains. That makes a model a drafting tool rather than an authority. A grid suits that role well: you get one draft per cell, you keep what is useful and rewrite the rest.

The order is the contract. If your page lists images from top-left to bottom-right, build the grid in that order and say so in the prompt: a 2×3 grid, reading order left to right then top to bottom, one alt text per cell, 120 characters maximum. You can then paste the answers back in order without matching them to files one by one. The same discipline is described for other AI tasks in combine images for AI.

Layouts that work: 2×3 for six images, which is a common batch for a product page or a gallery, 2×2 for four, and Strip of 3 for a short sequence where the order carries meaning. Leave about 8px of gap so two neighbouring descriptions do not blur into one.

A few practical rules before you start: use the sizes that will actually appear on the page, not your originals, because a different crop changes the subject and the description should match what visitors see. Remove anything private from the frame first, a face, a badge, a document in the background. On a screenshot, alt text usually means the text of the interface, so keep the cells large and the resolution high enough to read it.

A second pass is worth the effort. Ask for shorter versions: now give me the same six alt texts in 60 characters or less, keeping the product name. Machine drafts are usually too long and too literal, and cutting them in a second pass is faster than writing from scratch.

MergeFrame composites the grid in your browser, so unpublished product shots are not uploaded while you prepare the batch. The free plan covers 12 images per grid, 2 exports per day and PNG or JPG output up to 4000px, with no account and no watermark; imported files arrive six at a time. The 24-hour Pass at $3 removes the daily export limit for a day and adds PDF and WebP output.