Background: Peer recovery support services (PRSS) have been widely adopted across a variety of settings, but little is known about their economic impact.Objectives: To conduct a cost-effectiveness analysis of long-term, PRSS delivered after specialty substance use disorder (SUD) treatment (post-treatment), and to describe the development of a free, web-based cost-effectiveness calculator based on this analysis.Methods: Using publicly available data from a variety of sources, post-treatment PRSS were compared to specialty SUD treatment from the societal (broad perspective including costs like participant time) and health systems perspectives (only costs borne by health system), and in terms of quality-adjusted life years (QALYs) added and people in recovery. Whenever possible, 2019 data were used to avoid the impacts of COVID-19. Standard willingness-to-pay thresholds and additional treatment episode cost ($17,203.74) were used. One-way and probabilistic sensitivity analyses were conducted. Two recovery community organizations (RCOs) were involved in model refinement and calculator development in 2022.Results: Post-treatment PRSS were cost-effective to all thresholds and perspectives: $5,898.60 per QALY and $10,562.08 per person in recovery from the health system perspective, and $3,421.58 per QALY and $6,126.72 per person in recovery from the societal perspective, and post-treatment PRSS remained cost-effective across a variety of conditions in the sensitivity analyses. A cost-effectiveness calculator was developed from the analysis and is available at https://go.uth.edu/cea.Conclusions: In light of finding PRSS cost-effective, the expansion of PRSS across the US should continue, and may be aided by using the cost-effectiveness calculator to estimate tailored results for a specific program.