Weber-fresher law is the theory related with relationship between the magnitude of a physical stimulus and human perception such as If you see a friend who normally wears their hair long and they got a couple of inches cut off, you may not notice. if you see another friend who wear their hair short and they got a couple of inches cut off, you will certainly notice right away. Weber-fresher occur when you go shopping, If you see a sale for $1 off on a box of milk which discount from the old price $2.99 to $1.99 that might seem like a good deal for purchase and it can help you to money saved. But if you see a t-shirt, it cost $89.99 and sale for $1 off on a t-shirt that the customer may not be interested or notice on the price because the price still high. In this case, it can be seen that the two categories have discount prices as the same, but the customer have a notice with a box of milk more than t-shirt because most of people can perception with a small price than a big price which box of milk set up to selling as low when the seller discount $1, It’s make customer easier to perception and paying on it. That’s different from t-shirt, seller set up to sell as high price when they discount, customers were not interested because the seller reduce price was no different from the original. Weber-Fresher law can be applying in the price by study the perception or notice of consumer to purchase the product which has advantage and disadvantage between the marketer and consumer. The advantage of Weber-fresher affect to customer and marketer are Customers can get the price down but still keep the quality. The marketer has been a good response from customers, which it may customers confidence in the brand and become a brand loyalty. In the other hand, if the marketer have a promoted the brand by discount the price and reducing the size of the product without letting customers know. At first, the customer may not notice the size of its decline. Over time, customers notice the size of product decline that it may cause switch the brand.