what comes first height or width

Usually width comes first, then height when people write dimensions for 2D items like images, screens, or banners. For 3D objects, the common order is length × width × height.

Quick rule

• 2D: width × height.
• 3D: length × width × height.

Why it varies

Different fields use different conventions. Design and graphics often use width first, while packaging and technical specs often use length first for 3D objects.

Easy example

• A poster might be 24 × 36 meaning 24 wide, 36 high.
• A box might be 10 × 8 × 6 meaning length, width, height.

If you want, I can also give you the rule for photos, screens, boxes, and clothing sizes separately.