Conversion of Absolute Magnitude to Diameter

The following table lists the diameters of minor planets corresponding to the given values of the absolute magnitude, H. The diameter is to be read as kilometers when H is in the left-hand column or as meters when in the right-hand column. E.g., H = 8.0 corresponds to a diameter of 65 to 150 km, whereas H = 23.0 corresponds to a diameter of 65 to 150 m.

Conversion of H to a diameter for a specific object requires knowledge of the object's albedo. This quantity is not known for most objects, so the diameters listed here are given as ranges: the smaller value corresponding to an albedo of 0.25 and the larger to an albedo of 0.05. Most objects have albedos in this range. If a specific object has an albedo < 0.05, the diameter will be larger than the upper limit listed here. If the albedo > 0.25, the diameter will be smaller than the lower limit given here.

            H        Diameter       H  
          
            3.0     670 - 1500     18.0
            3.5     530 - 1200     18.5
            4.0     420 -  940     19.0
            4.5     330 -  740     19.5
            5.0     260 -  590     20.0
            5.5     210 -  470     20.5
            6.0     170 -  370     21.0
            6.5     130 -  300     21.5
            7.0     110 -  240     22.0
            7.5      85 -  190     22.5
            8.0      65 -  150     23.0
            8.5      50 -  120     23.5
            9.0      40 -   95     24.0
            9.5      35 -   75     24.5
           10.0      25 -   60     25.0
           10.5      20 -   50     25.5
           11.0      17 -   37     26.0
           11.5      13 -   30     26.5
           12.0      11 -   24     27.0
           12.5       8 -   19     27.5
           13.0       7 -   15     28.0
           13.5       5 -   12     28.5
           14.0       4 -    9     29.0
           14.5       3 -    7     29.5
           15.0       3 -    6     30.0
           15.5       2 -    5           
           16.0       2 -    4       
           16.5       1 -    3       
           17.0       1 -    2
           17.5       1 -    2

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