Methods and systems for amplitude estimation and gain adjustment using noise as a reference are described. An example receiver can include an antenna and a front end amplifier coupled to the antenna. The receiver can also include a detector circuit coupled to the front end amplifier. The receiver can be configured to determine a power of a received signal at the antenna based on a gain of the receiver. The gain of the receiver can be determined based on a noise figure of the front end amplifier and a noise amplitude.