How does the landlord know whether his rent is high or low?

Through the comparison of surrounding houses or professional consultation. Landlords can observe the rent prices of similar houses around them, compare the rents of houses in the same area, type, area and facilities, get a rough market price range, and judge whether their rents are high or low. They can also consult real estate agents, appraisers or leasing professional organizations, give comments and suggestions on the rent level according to market experience and professional knowledge, and judge whether their rent is high or low.