Diameter measurements of Arcturus made by various groups since 1980 using interferometric techniques. K-band measures are from I2T, IOTA, and VLTI, the H-band data point is from IOTA, the visible measures are made by the Mark III interferometer and NPOI, and the purple square indicates the measure presented here. Vertical error bars are included for all measures, and the horizontal error bars indicate the time frame over which the observations were taken in each case. For our measure, though the timeline extends from our earliest observations in 2017 to the present, most of the data are from 2025. The black solid and dotted lines indicate the weighted average and uncertainty found in I. Ramírez & C. Allende Prieto (2011), 21.06 ± 0.17 mas.