Assumptions of the Law of Supply : The law of supply is conditional. It is based on certain assumptions. 

They are as follows:

1. No change in Cost of Production: The law will hold true only if the cost of production remains constant.

2. No change in Technique of Production : It is assumed that there is no change in the method of production. If there is any improvement in the technique of production then supply will increase at the same price.

3. No change in Weather condition : Changes in weather and climatic condition would affect supply especially of agricultural products, so it is assumed to remain constant. 

4. No change in Government Policies : Any change in government policies will affect the supply, so it is assumed that there is no change in government tax policies, subsidies or industrial policy. 

5. No Speculations about Future Prices : It is assumed that the producers do not speculate about future changes in price.

6. No change in Transport Cost : It is assumed that there is no change in transport facility and transport cost. 

7. Prices of Other Goods : It is assumed that the prices of competitive goods remain constant. If the price of competitive goods rises then it is quite likely that producer may transfer his resource to the production of those goods, whose price has arisen. 

8. No change in the quantity of goods kept for Self – consumption : If sellers keep more goods for their personal use then supply cannot be increased even at a high price. 

9. Constant Scale of Production : It is assumed that the scale of production remains constant during the given period of time.