What is the densest known planet?
A density needs a mass and a radius measured independently, and only 2,457 of the 6,370 confirmed exoplanets here have a mass that was measured rather than estimated from the radius itself: among the rocky worlds in that group, the densest is Kepler-406 b at 11.97 g/cm³, more than twice the density of Earth. Everything about Kepler-406 b →
| # | World | Density | Distance |
|---|---|---|---|
| ★ 1 | Kepler-406 b | 11.97 g/cm³ | 1,187 ly |
| 2 | TOI-201 d | 11.90 g/cm³ | 371 ly |
| 3 | TOI-2076 e | 11.76 g/cm³ | 137 ly |
| 4 | TOI-1238 b | 11.69 g/cm³ | 231 ly |
| 5 | KOI-94 b | 11.57 g/cm³ | 1,556 ly |
| 6 | TOI-2095 b | 11.57 g/cm³ | 137 ly |
| 7 | WASP-84 c | 11.30 g/cm³ | 328 ly |
| 8 | EPIC 201595106 b | 11.03 g/cm³ | 757 ly |
| 9 | K2-38 b | 11.01 g/cm³ | 628 ly |
| 10 | Kepler-102 d | 10.76 g/cm³ | 352 ly |
| 11 | Kepler-113 b | 10.69 g/cm³ | 856 ly |
| 12 | Kepler-101 c | 10.66 g/cm³ | 3,027 ly |
| 13 | Kepler-42 d | 10.65 g/cm³ | 131 ly |
| 14 | TOI-1347 b | 10.49 g/cm³ | 481 ly |
| 15 | Kepler-99 b | 10.45 g/cm³ | 680 ly |
| 16 | Kepler-62 d | 10.40 g/cm³ | 981 ly |
| 17 | Kepler-80 d | 10.38 g/cm³ | 1,205 ly |
| 18 | Kepler-105 c | 10.33 g/cm³ | 1,498 ly |
| 19 | EPIC 220674823 b | 10.03 g/cm³ | 798 ly |
| 20 | HD 137496 b | 9.90 g/cm³ | 507 ly |
| 21 | TOI-1798.02 | 9.83 g/cm³ | 369 ly |
| 22 | Kepler-323 c | 9.68 g/cm³ | 1,484 ly |
| 23 | Kepler-20 b | 9.59 g/cm³ | 922 ly |
| 24 | TOI-1075 b | 9.54 g/cm³ | 200 ly |
| 25 | TOI-4311 b | 9.52 g/cm³ | 440 ly |
Showing the top 25 of 218 that qualify.
This is the record that most needs its caveat said out loud. Roughly half the masses in any exoplanet catalog are not measurements at all: they are inferred from the planet's radius using an average relationship between size and mass. Compute a density from one of those and you have simply divided a number by the number it was derived from, which produces a figure that looks precise and means nothing. Only directly measured masses are ranked here.
Even among measured masses, a mass and a radius are often published by different teams from different data, and a mismatched pair can imply a density heavier than any material. This table is therefore held to worlds under two Earth radii, where a rocky composition is physically expected, and to implied densities between 3 and 12 grams per cubic centimetre: the range that runs from stone to a fully compressed iron core. Earth sits at 5.5 and Mercury, the densest planet in our own system for its size, at 5.4.
What is the densest known planet?
A density needs a mass and a radius measured independently, and only 2,457 of the 6,370 confirmed exoplanets here have a mass that was measured rather than estimated from the radius itself: among the rocky worlds in that group, the densest is Kepler-406 b at 11.97 g/cm³, more than twice the density of Earth.
Why is the densest planet not simply the heaviest one?
Because density is mass divided by volume. A gas giant can weigh three hundred times what Earth weighs and still be lighter, cubic metre for cubic metre, than water. The densest worlds are small, rocky and iron-rich, not large.
How dense can a planet actually be?
A world made almost entirely of iron, compressed by its own gravity, tops out near 12 to 13 grams per cubic centimetre. Any catalogued value far above that is a sign that the mass and the radius came from different measurements of different things, which is why this ranking stops there.
How many planets have both a measured mass and a radius?
2,416 do, out of 6,370 confirmed exoplanets. That subset is the only place a real density can be computed, and the 25 rocky worlds inside it are what this table ranks.
Keep exploring: all records · the strongest surface gravity · what surface gravity means