Convert pixels to a print size at any DPI, and see the pixels you need for common sizes.
Print size is just pixels divided by DPI. At 300 DPI, a 3000 px wide file prints 10 inches wide and stays crisp. Drop to 150 DPI and the same file stretches to 20 inches but gets softer. Work backwards for a target size: an 11 by 14 inch print at 300 DPI needs 3300 by 4200 px. Always design at the largest size you will sell, then scale down, never up.
300 DPI is the standard for crisp prints. 150 DPI is the rough minimum for direct-to-garment apparel. 72 DPI is screen only.
The file does not have enough pixels for that size. Either print smaller or generate the art at higher resolution. Upscaling a small file does not add real detail.
No, this is pure math in your browser.