The five presets ImagePipe provides (product_card, product_page, category_banner, manufacturer_logo, mobile_thumbnail) are calibrated for standard WooCommerce spots. A custom theme — a 5-column catalog grid instead of 4, a full-width zoomable product gallery — almost always displays its images at real dimensions that differ from the defaults.
To find the right target dimension: inspect the displayed element in your browser's developer tools (the actually rendered CSS width and height, not the original file size), then multiply by 1.5 to 2 to cover high pixel-density screens (retina). A systematic ×2 factor also doubles the weight of every generated variant, for a sharpness gain rarely perceptible beyond ×1.5 on a typical product photo.
Reconfigure an existing preset rather than creating a new one: change product_card's target dimensions directly in the settings rather than multiplying custom presets for each spot — simpler to maintain over time. Variants already cached under the old setting stay valid until explicitly cleared (see the guide on clearing the cache after a theme change).
The resize mode matters as much as the size itself: a catalog grid with product photos of varying ratios almost always needs Cover or Crop to stay visually consistent, while a category banner often needs to stay in Contain mode so the visual is never cropped. A preset with the wrong size but the right mode is usually more visually acceptable than the reverse.