List of smallest exoplanets


Below is a list of the smallest exoplanets so far discovered, in terms of physical size, ordered by radius.

List

The sizes are listed in units of Earth radii. All planets listed are smaller than Earth and up to 1 Earth radii. The NASA Exoplanet Archive is used as the main data source. Radii listed in italics are estimates.
ExoplanetRadius Notes and referencesMass
SDSS J0845+2257 b0.01-0.013Planetesimal, enhanced in iron and silicates.-
WD 1145+017 b~0.03Disintegrating planetesimal, likely one of several orbiting its star. Likely about one-tenth the mass of Ceres and ~200 km in radius.~0.000016
Ceres0.0742Shown for comparison-
Pluto0.1863Shown for comparison-
Moon0.2725Shown for comparison-
Kepler-37bSmallest known exoplanet.<0.79
BD+05 4868 Ab~0.314Disintegrating planet, radius is just an estimate.0.02
PSR B1257+12 b ~0.338Least massive known exoplanet, at 0.02 Earth masses. Radius predicted from mass-radius relationship.0.02
Kepler-1520b≲0.36Disintegrating planets with poorly known radii, all thought to be smaller than Mercury.-
KOI-2700b≲0.36Disintegrating planets with poorly known radii, all thought to be smaller than Mercury.-
K2-22b≲0.36Disintegrating planets with poorly known radii, all thought to be smaller than Mercury.-
Mercury0.3826Shown for comparison-
Kepler-879c-
Kepler-444b-
Ganymede0.413Shown for comparison-
Kepler-158d-
Kepler-102b-
Kepler-444c-
Kepler-1971b -
Kepler-1489c-
Kepler-1994b-
Kepler-1308b-
Kepler-444d-
Mars0.5325Shown for comparison-
Kepler-62c-
Kepler-444e-
Gliese 238 b-
Kepler-102c-
Kepler-42d-
Kepler-1583b-
Kepler-1998b-
Kepler-963c-
Kepler-974c Candidate., the Exoplanet Archive lists it as confirmed.-
Kepler-1087b-
K2-89b-
Kepler-1877b0.624-
Barnard's Star e~0.637Radius predicted from mass-radius relationship. Least massive exoplanet detected by radial velocity and possibly smallest known within 10 parsecs.-
K2-137bThe discovery paper finds a larger radius of -
Kepler-1371c-
Kepler-138b-
Kepler-1130d0.645-
Kepler-1351b-
Kepler-1542c-
Kepler-271d-
Kepler-431c0.668-
Kepler-1558b-
LHS 1678 b-
K2-116b-
Kepler-141b-
K2-297b -
Proxima Centauri d~0.692Radius predicted from mass-radius relationship.-
Barnard's Star d~0.694Radius predicted from mass-radius relationship.-
Gliese 367 b Smallest exoplanet within 10 parsecs with a measured radius.0.633
Kepler-2003b -
Kepler-378c--

Excluded objects

Kepler-37e is listed with a radius of in the Exoplanet Archive based on KOI data, but the existence of this planet is doubtful, and assuming its existence, a 2023 study found a mass of, inconsistent with such a small radius.
KOI-6705.01, listed as a potential very small planet in the KOI dataset, was shown to be a false positive in 2016.

Candidate planets

Below is a list of candidate planets below. These planets have yet to be confirmed.
Kepler object of interestRadius Notes and references
SDSS J1228+1040 b
0.010Extrasolar planetesimal. Likely a remnant iron core. Radius is in the range of 1.2 – 120 km. Has been disputed in a 2023 publication.
TRAPPIST-1i
KOI-4582.010.35
KOI-2298.030.36
KOI-2169.040.37
KOI-7174.010.37
KOI-8012.010.42
KOI-6860.010.43
KOI-2059.020.44
KOI-304.020.46
KOI-7793.010.46
KOI-2678.020.48
KOI-6631.010.48
KOI-2421.020.48
KOI-5974.010.49
KOI-3444.030.5
KOI-2295.010.52
KOI-7863.010.52
KOI-2612.020.53
KOI-4657.010.54
KOI-8257.010.54
KOI-115.03
KOI-2421.010.55
KOI-4097.020.55
KOI-7645.010.55
KOI-3208.010.56
KOI-6763.010.56
KOI-2859.030.57
KOI-4146.020.57
KOI-2859.040.57
KOI-7873.010.57
TOI-4307.02
KOI-2657.010.58
KOI-8277.010.58
KOI-4296.010.59
KOI-3196.010.59
KOI-5692.010.59
KOI-1964.010.6
KOI-4407.010.6
KOI-4871.010.6
KOI-5211.010.6
KOI-7888.010.6
KOI-3184.030.6
KOI-8183.010.6
KOI-3083.020.61
KOI-4421.010.61
KOI-4716.010.61
KOI-3102.010.61
KOI-7032.010.61
KOI-1499.020.62
KOI-605.020.62
KOI-7676.010.62
KOI-4849.010.62
KOI-365.020.62
KOI-7116.010.62
KOI-4421.020.62
KOI-7949.010.62
KOI-2029.040.63
KOI-6889.010.63
KOI-2636.020.63
KOI-3248.010.64
KOI-5213.010.64
KOI-6276.010.64
KOI-7617.010.64
KOI-7903.010.64
KOI-7925.010.64
KOI-8174.010.64
KOI-3083.030.65
KOI-4875.010.65
KOI-4808.010.65
KOI-6568.010.65
KOI-1619.010.66
KOI-3111.020.66
KOI-2859.050.66
KOI-3017.010.67
KOI-4907.010.67
KOI-1616.020.67
KOI-6299.010.67
KOI-8211.010.67
KOI-2593.020.68
KOI-4605.010.68
KOI-7832.010.68
KOI-7483.010.68
KOI-2623.020.68
KOI-7924.010.68
KOI-7628.010.69
KOI-4129.010.69
KOI-4822.010.69
KOI-6600.010.69