This report applies IDMC's original methodology to assess the economic impact of internal displacement in 2020 in 18 countries. Internal displacement affects the wellbeing and the welfare of internally displaced people (IDPs) in numerous ways. It can lead to a deterioration of their health, security, social life, housing conditions, livelihoods, environments and education. People in the host community can also be affected, particularly in the case of mass, protracted displacement. All of these impacts have repercussions not only on the lives of affected people, but also on the economy. IDMC developed an original methodology to measure the economic impact of internal displacement, including the direct cost of providing every IDP with support for housing, education, health and security, and their estimated loss of income. The economic impact of internal displacement in 2020 ranged from $109 per IDP for a year of displacement in Afghanistan to $830 per IDP in Syria. The average cost of providing each IDP with support for housing, education, health and security, and their loss of income for one year of displacement was estimated at $370 on 2020. With about 55 million people living in internal displacement as a result of conflict, violence and disasters at the end of 2020, this produces a total global economic impact of nearly $20.5 billion. Covid-19 influenced the cost of internal displacement by creating new needs, exacerbating existing vulnerabilites for IDPs and producing obstacles to the delivery of humanitarian aid.