The concept of circularity has gained momentum in recent years to reduce the amount of waste generated by a construction project and the need for new materials. This paper explores the different circularity potentials of using 1 m2 of biobased insulation materials (BbIMs) with various origins (plants, animals, or recycled) and forms (loose fill, blocks or panels) along 100 years. The BbIMs under investigation are commercial insulations including straw, cork, wood fiber, wood wool, prairie grass, cellulose, cotton, sheep wool, and hemp. The circularity potentials of these insulations are evaluated by calculating the Material Circularity Indicator (MCI). The findings highlight varying circularity potential among the different BbIMs, with the MCI ranging from 0.18 to 0.9. Notably, cellulose insulation, both blown and in panel forms, achieved the highest circularity scores due to their significant content of recycled and renewable materials and efficient recycling processes at end-of-life (EoL). The results emphasize the importance of designing insulation solutions with closed-loop systems to promote circularity.