how big is a mustard seed

A mustard seed is typically about 0.9 to 2.5 millimeters in diameter, depending on the variety. Common sizes are approximately 1 to 1.5 mm for yellow and brown mustard seeds, and 0.9 to 1.1 mm for black mustard seeds. Some sources mention up to 2.5 mm, but the usual range is around 1 mm, making it smaller than many other common seeds and spices.