| Conduction | Convection | Radiation |
| Heat is transferred without the actual movement of the molecules | Heat transfer takes place due to the movement of the molecules themselves. | Heat is transferred without a medium. |
| Conduction is possible only in solids with the exception of mercury which is a liquid | Convection takes place in liquids and gases only. | Radiation requires no medium. It takes place even in vacuum. |
| Transfer is slow | Transfer is faster | Transfer is the fastest |
| Heat transfer can be in any direction | Heat transfer is mainly upwards. | Heat transfer takes place in all direction. |