The sizes are listed in units of Earth radii (R🜨). All planets listed are smaller than Earth and Venus, up to 0.7 Earth radii. The NASA Exoplanet Archive is used as the main data source.[1][2] Radii listed in italics are estimates.
More information Exoplanet, Radius (R🜨) ...
| Exoplanet |
Radius (R🜨) |
Notes and references |
|---|
| SDSS J0845+2257 b |
0.01-0.013 |
Planetesimal, enhanced in iron and silicates. [3] |
| WD 1145+017 b |
~0.03[4] |
Disintegrating planetesimal, likely one of several orbiting its star. Likely about one-tenth the mass of Ceres and ~200 km in radius.[4] |
| Ceres |
0.0742 |
Shown for comparison |
| Pluto |
0.1863 |
Shown for comparison |
| Moon |
0.2725 |
Shown for comparison |
| Kepler-37b |
0.3098+0.0059
−0.0076 |
Smallest known exoplanet.[5][6] |
| BD+05 4868 Ab |
~0.314 |
Disintegrating planet, radius is just an estimate.[7] |
| PSR B1257+12 b (Draugr) |
~0.338 |
Least massive known exoplanet, at 0.02 Earth masses. Radius predicted from mass-radius relationship.[8] |
| Kepler-1520b |
≲0.36 |
Disintegrating planets with poorly known radii, all thought to be smaller than Mercury.[9][10] |
| KOI-2700b |
| K2-22b |
| Mercury |
0.3826 |
Shown for comparison |
| Kepler-879c |
0.4±0.1 |
[11] |
| Kepler-444b |
0.403+0.016
−0.014 |
[12] |
| Ganymede |
0.413 |
Shown for comparison |
| Kepler-158d |
0.43±0.05 |
[11] |
| Kepler-102b |
0.460±0.026 |
[6] |
| Kepler-444c |
0.497+0.021
−0.017 |
[12] |
| Kepler-1971b (KOI-4777.01) |
0.51±0.03 |
[13] |
| Kepler-1489c |
0.51±0.08 |
[11] |
| Kepler-1994b |
0.51+0.06
−0.05 |
[14] |
| Kepler-1308b |
0.52+0.06
−0.05 |
|
| Kepler-444d |
0.530+0.022
−0.019 |
[12] |
| Mars |
0.5325 |
Shown for comparison |
| Kepler-62c |
0.54±0.03 |
|
| Kepler-444e |
0.546+0.017
−0.015 |
[12] |
| Gliese 238 b |
0.566±0.014 |
[15] |
| Kepler-102c |
0.567±0.028 |
[6] |
| Kepler-42d |
0.57±0.18 |
|
| Kepler-1583b |
0.60+0.09
−0.05 |
|
| Kepler-1998b |
0.6+0.08
−0.04 |
[16] |
| Kepler-963c |
0.6±0.2 |
[11] |
| Kepler-974c (KOI-1843.03) |
0.61+0.12
−0.08 |
Candidate.[17] As of 2025[update], the Exoplanet Archive lists it as confirmed.[2] |
| Kepler-1087b |
0.61+0.17
−0.05 |
|
| K2-89b |
0.615±0.080 |
|
| Kepler-1877b |
0.624 |
|
| Barnard's Star e |
~0.637 |
Radius predicted from mass-radius relationship.[2] Least massive exoplanet detected by radial velocity and possibly smallest known within 10 parsecs.[18] |
| K2-137b |
0.64±0.10[19] |
The discovery paper finds a larger radius of 0.89±0.09 R🜨[20] |
| Kepler-1371c |
0.64+0.07
−0.05 |
|
| Kepler-138b |
0.64±0.02 |
[21] |
| Kepler-1130d |
0.645 |
|
| Kepler-1351b |
0.65+0.05
−0.04 |
|
| Kepler-1542c |
0.65+0.09
−0.06 |
|
| Kepler-271d |
0.66±0.05 |
|
| Kepler-431c |
0.668 |
|
| Kepler-1558b |
0.68+0.06
−0.04 |
|
| LHS 1678 b |
0.685+0.037
−0.035 |
[22] |
| K2-116b |
0.69±0.04 |
|
| Kepler-141b |
0.69±0.05 |
|
| K2-297b (EPIC 201497682 b) |
0.692+0.059
−0.048 |
|
| Barnard's Star d |
~0.694 |
Radius predicted from mass-radius relationship.[2][18] |
| Gliese 367 b (Tahay) |
0.699±0.024 |
Smallest exoplanet within 10 parsecs with a measured radius.[23] |
| Kepler-2003b (KOI-4978.02) |
0.7±0.1 |
[11] |
| Kepler-378c |
0.70±0.05 |
|
Close
Excluded objects
Kepler-37e is listed with a radius of 0.37±0.18 R🜨 in the Exoplanet Archive based on KOI data, but the existence of this planet is doubtful,[24] and assuming its existence, a 2023 study found a mass of 8.1±1.7 M🜨, inconsistent with such a small radius.[25]
KOI-6705.01, listed as a potential very small planet in the KOI dataset, was shown to be a false positive in 2016.[26]
