Ostrich eggs are the largest of all eggs , though they are actually the smallest eggs relative to the size of the adult bird - on average they are 15 cm ( 5.9 in ) long , 13 cm ( 5.1 in ) wide , and weigh 1.4 kilograms ( 3.1 lb ) , over 20 times the weight of a chicken 's egg and only 1 to 4 % the size of the female .
- on average they are 15 centimetres ( 5.9 in ) long , 13 centimetres ( 5.1 in ) wide , and weigh 1.4 kilograms ( 3.1 lb ) , over 20 times the weight of a chicken egg .