Measure the actual top
Use a ruler to measure the flat square you intend to decorate, edge to edge. Cap styles vary, so a generic size is only a planning range. Record the usable area inside any seam or raised edge. Find the center button or tassel attachment and measure its position, since a large word or face directly beneath it may become hidden.
Choose the width
The maker accepts an intended square width from eight to ten inches. Choose a value based on your measured usable area, not on a photo of someone else’s cap. The SVG file records that physical width in its dimensions. It remains a digital design sketch until you print or transfer it using a setup that preserves that size.
Understand Letter output
A nine- or ten-inch square will not fit at actual size inside an ordinary Letter page with margins. The Print planning sketch button intentionally scales the design to fit a Letter page. Use that page to review words and composition. Do not trace it as a full-size cap template unless you separately enlarge it and confirm dimensions with a ruler.
Plan full-size transfer
A compatible vector editor or print service can open the SVG and tile it across pages or use larger paper. Confirm that scaling is 100 percent and that the assembled square matches the measured width. Make a paper mock-up, place it on the cap, and check the button and edges. If it overlaps a seam, reduce the design or shift its content.
Try this next
Write measurements in both inches and millimeters if the person printing the final piece uses different units. Keep the actual ruler beside the assembled paper mock-up for a photograph. That record can help resolve a scale disagreement later without treating the browser preview as physical evidence.
Have a correction or a suggestion? Tell the studio.