how to resize different sprite into same size and assign to a game object ?

I want to resize sprite to same size and assign to my gameobject so that all sprite look a like my code is below` %|-1861673298_1|% %|1456770366_2|% public Sprite img1; %|524112416_4|% void Start() %|1415432336_6|% %|238004631_7|% %|449706484_8|% %|385360838_9|% %|1152204952_10|% %|769354091_11|% %|-782662156_12|% %|1999571366_13|% %|-473783116_14|% %|1892526277_15|% ` when i am changind my sprite in update function the sprite becomes so big as img2 is large scale sprite .but i want to img1 and img2 be same size when it renders in gameobject these . But i have no idea how ot maintain a certain value it would be very helpful if any one can help me here to resize both sprite to same size;