Loading page
About this tool
Build a structured Canva AI design prompt with the exact canvas size, aspect ratio, brand slots and a legibility-checked copy budget.
The Canva AI Prompt Builder writes a structured design brief that pins down the four things generative design tools get wrong without instruction: exact canvas size, aspect ratio, brand palette and type, and how much copy actually fits. Canvas sizes are real Canva presets (Instagram post 1080 x 1080, YouTube thumbnail 1280 x 720, A4 poster 2480 x 3508 at 300 DPI), aspect ratios are reduced with the greatest common divisor, and the character budget is derived from a 16 px minimum rendered text size at the smallest width the design is normally viewed at. It is for marketers and small-business owners who want on-brand output rather than a lucky first draft.
Open Canva AI Prompt Builder on AltFTool — it loads instantly in your browser.
Provide your input — an image, text, or data.
Let the tool analyze or generate the result.
Review, refine, and reuse the output wherever you need it.
Every format carries its actual Canva pixel size and reduced aspect ratio, so nothing gets cropped on export.
Headline and supporting-line limits come from a 16 px minimum readable size, not from guesswork about brevity.
Palette and type are stated as constraints with a dominant colour, which is what stops output drifting off brand between options.
1080 x 1080 pixels for a square feed post and 1080 x 1920 for a Story or Reel cover. A square post is rendered around 470 px wide in the feed, so text set smaller than roughly 37 px on the 1080 px canvas falls below the 16 px readable floor once it is displayed.
It depends on the canvas and how small it is viewed. On a YouTube thumbnail seen at about 210 px wide in a results grid, the readable budget is around 22 characters across two lines; on an A4 poster read at arm's length it is closer to 85. This tool calculates the number for whichever format you pick.
State the canvas size and format first, then the subject and audience, then the brand palette and fonts as hard constraints, then the exact copy you want set, then a named visual direction, and finally what to leave out. Ambiguity is what produces generic output, so an explicit 'do not' list matters as much as the brief itself.
300 DPI. At 300 DPI an A4 page is 2480 x 3508 pixels and a US business card is 1050 x 600 pixels. Export as PDF Print with CMYK and 3 mm bleed, and keep all text roughly 7% in from every edge so nothing is lost when the sheet is trimmed.