What Is Mars Gravity Compared to Earth?

Mars pulls on objects with a surface gravitational acceleration of about 3.71 meters per second squared, compared to Earth’s 9.81 m/s², making Martian gravity roughly 38% of what you feel right now. A person who weighs 150 pounds on Earth would weigh about 57 pounds on Mars, though their body mass would remain exactly the same. That simple ratio, sometimes written as 0.38 g, ripples outward into everything from how rivers would carve valleys to how your muscles would waste away over months of living there.

Where the Difference Comes From

Surface gravity depends on two things: how much mass a planet has and how far you are from its center. Mars has only about one-tenth the mass of Earth, and its radius is roughly half of Earth’s. Since gravity weakens with distance, the smaller radius partly compensates for the lower mass, but not nearly enough. The net result is that gravitational pull at the Martian surface lands at just over a third of Earth’s.

This is not an approximate or uncertain number. Decades of spacecraft tracking have pinned it down precisely. The Mars Global Surveyor mission, for instance, mapped the planet’s gravitational field in detail by measuring how the spacecraft sped up or slowed down as it orbited over regions of varying density.

How Moving on Mars Would Actually Feel

Walking at 0.38 g is not simply a lighter version of walking on Earth. Your legs, ankles, and feet would reorganize the way they fire and flex. Experiments using NASA’s Active Response Gravity Offload System, which suspends people in harnesses to simulate reduced gravity, found that muscle activation in the lower legs changes significantly under simulated Martian conditions, with altered patterns of dorsiflexion and plantar flexion that shift how you push off and land with each step.¹ The researchers noted that these changes raise the risk of tripping and falling, because the feedback your body uses to stay balanced no longer matches what your nervous system expects.

A separate isolation experiment, SIRIUS-19, studied how people adapted to simulated Martian and lunar unloading over a four-month confinement. When subjects walked at 0.35 g, their gait restructured in measurable ways: proprioceptive and support signals shifted enough to produce entirely new movement patterns.² Sensorimotor systems that normally rely on gravity to orient you in space would need to recalibrate, affecting not just walking but reaching, lifting, and judging verticality.³

One interesting finding from biomechanics research is that skipping, which looks absurd on Earth, becomes a surprisingly efficient way to move at very low gravity levels. At lunar gravity (0.17 g), skipping and running converge in metabolic cost to something close to walking on Earth. At Martian gravity the difference between skipping and running is still noticeable, but both bouncing gaits are substantially cheaper in energy than they would be here.⁴ Apollo astronauts famously resorted to a loping, bouncing stride on the Moon; on Mars, you would probably settle into something closer to a normal jog, just a lighter one.

What 0.38 g Does to Your Body Over Time

The immediate sensory experience of Martian gravity might feel liberating, but the long-term physiological effects are a serious concern for future Mars settlers. A meta-analysis of rodent studies on partial weight-bearing found that loading at roughly 40% of normal body weight, close to the Martian equivalent, caused rapid deconditioning of skeletal muscle within the first one to two weeks. Higher levels of partial loading slowed the decline but could not prevent it entirely.⁵ The takeaway is sobering: Mars gravity is probably not enough mechanical stimulus to maintain muscle and bone health without deliberate countermeasures like resistance training.

The cardiovascular system responds to partial gravity in its own peculiar way. Parabolic flight studies show that heart rate and blood pressure both drop as gravity decreases, while heart-rate variability increases. Under simulated Martian gravity specifically, researchers observed a triphasic cardiovascular response pattern, distinct from the biphasic pattern seen at lunar or zero gravity.⁶ This suggests the body does not simply interpolate between Earth and weightlessness; each partial-gravity level provokes a qualitatively different autonomic response. Whether that triphasic pattern is benign or harmful over months and years is something nobody yet knows, because parabolic flights last seconds, not seasons.

NASA’s Active Response Gravity Offload experiments also flagged an underappreciated problem: walking and running at reduced gravity burns less energy than on Earth. That sounds appealing until you realize that astronauts on long Mars missions would need exercise regimes specifically designed to stress their bodies enough to prevent atrophy. An easy jog on Mars might provide such little loading that it is nearly counterproductive as exercise.¹

How Weaker Gravity Shaped the Martian Landscape

Mars is not just a smaller Earth. Its lower gravity has driven geological processes in directions that produced a dramatically different surface. The most obvious result is scale: Martian volcanoes and canyons are vastly larger than their terrestrial counterparts. Olympus Mons, the tallest volcano in the solar system, rises nearly 22 kilometers above the surrounding plains. On Earth, the crust could not support a structure that tall because our stronger gravity would cause it to sag and spread. Mars’ weaker pull lets rock pile higher before deforming.

Explosive volcanism on Mars was also shaped by a combination of low gravity and extremely low atmospheric pressure (roughly 600 to 1,000 pascals, compared to Earth’s 100,000). Researchers have theorized that even magmas with very small amounts of dissolved gas could fragment explosively under Martian conditions, because the lower confining pressure allows bubbles to expand far more readily.⁷ This means Mars may have had more explosive eruptions than you would expect from such a geologically quiet planet.

Impact craters also behave differently. A study of complex craters across several planets found that both the depth of craters and the diameter at which craters transition from simple bowl shapes to more complex forms with central peaks vary inversely with surface gravity.⁸ On Mars, a smaller impactor can produce a complex crater, and craters of a given diameter tend to be shallower than on a higher-gravity world. The weaker gravitational pull means the excavated material does not collapse inward as aggressively.

Even rivers, or the channels that ancient Martian rivers carved, show the fingerprints of reduced gravity. Modeling of sediment transport under lower gravitational acceleration predicts that suspended-load-dominated channels should develop gentler slopes on Mars than on Earth, not steeper ones as some earlier hydraulic models suggested.⁹ The reduced gravity slightly increases the potential to carry sediment in suspension, which means Martian rivers could have moved material efficiently even on very gentle gradients.

Gravity Is Not Uniform Across Mars

Just as Earth’s gravitational field has bumps and dips caused by mountain ranges, ocean trenches, and differences in crustal density, Mars has its own gravitational landscape, and it is more lopsided than Earth’s. The planet’s most striking feature is a hemispheric divide: the southern highlands are rough and elevated but gravitationally bland, sitting close to a balanced, compensated state. The northern lowlands, which are smoother and lower in elevation, display a much wider range of gravitational anomalies, indicating a thinner but more rigid crust.¹⁰

Detailed gravity mapping has revealed that Olympus Mons produces the largest known gravity anomaly in the solar system, a local surplus of gravitational pull caused by the sheer mass of volcanic rock piled up there. Several large impact basins, including Hellas, Argyre, Utopia, and Isidis Planitia, contain mascons (mass concentrations), regions where dense material beneath the surface creates a measurable gravitational high. Isidis Planitia has the highest-amplitude mascon on Mars.¹¹ These gravity anomalies are not things you would feel standing on the surface, but they matter enormously for spacecraft navigation: an orbiter passing over a mascon gets tugged slightly off course, and mission planners have to account for this.

More recent modeling work has attempted to disentangle the contributions of lithospheric flexure and deep mantle flow to Mars’ gravity field, with the remaining short-scale residuals revealing information about crustal density that appears to correlate with known geological structures.¹² In other words, Mars’ gravity map is becoming a tool for understanding what lies beneath the surface, much as seismic surveys are on Earth.

Growing Plants Under Martian Gravity

If humans are going to live on Mars for extended periods, they will need to grow food there. Plant biology under reduced gravity is far from straightforward. On Earth, roots grow downward because gravity tells them where “down” is through a mechanism called gravitropism. In microgravity, that signal disappears. Under Martian gravity, the signal is weaker but still present, and researchers are trying to figure out whether 0.38 g provides enough of a cue for normal root development.

Experiments on the International Space Station have shown that in low-light conditions, roots in microgravity grow in essentially random directions. Under blue or red light, however, the roots display phototropic curvature, bending toward or away from light, a response that is reduced or absent at higher gravity levels.¹³ This suggests that gravity and light jointly steer root growth, and when gravity fades, light takes on a larger role. On Mars, with its partial gravity, the interplay between these two signals remains an open question.

Ground-based simulations of fractional gravity have produced concerning results for plant cell biology. At simulated lunar gravity (0.17 g), cells in root growth zones showed increased local proliferation rates but decreased protein synthesis, disrupting the balance between cell growth and cell division that healthy root tips depend on.¹⁴ Whether Martian gravity, at more than twice the lunar level, provides enough loading to avoid this kind of disruption is one of the key questions for space agriculture. The answer will likely determine whether a Mars greenhouse can rely on the planet’s natural gravity or will need rotating platforms or other engineering tricks to simulate heavier conditions.

Simulating Martian Gravity on Earth

Nobody has actually stood on Mars yet, so everything we know about living at 0.38 g comes from simulations. Researchers use several methods, each with trade-offs. Parabolic flights produce brief periods of reduced gravity, useful for cardiovascular and perceptual studies but far too short for muscle-deconditioning research. Harness-based systems like NASA’s ARGOS suspend people to offload a fraction of their weight, allowing longer-duration gait and movement studies. Partial-weight-bearing rigs for rodents enable months of exposure but cannot perfectly replicate the uniform body-wide unloading of actual reduced gravity.

A more exotic approach uses intense, inhomogeneous magnetic fields to exert forces on biological specimens that partially cancel out gravity. The idea behind such magnetic levitation simulators is that by adjusting the field, researchers can continuously tune the effective gravitational load from zero to full Earth gravity, creating a simulated Martian or lunar environment for cells, tissues, or small organisms in a controlled laboratory setting.¹⁵ Each of these methods captures something different about the partial-gravity experience, and none captures all of it. The honest state of knowledge is that we have solid data on zero gravity from the ISS, reasonable models of partial gravity from ground simulators, and no direct human data from Mars itself.

What Martian Gravity Means for Its Moons

Mars has two tiny moons, Phobos and Deimos, and the planet’s gravitational influence is slowly destroying the closer one. Phobos orbits only about 6,000 kilometers above the Martian surface, far closer than any other known moon to its parent planet. At that distance, the tidal forces generated by Mars’ gravity are gradually draining energy from Phobos’ orbit, causing it to spiral inward.

Laser altimeter observations from the Mars Global Surveyor spacecraft measured Phobos’ orbital acceleration with high precision and found that the energy dissipation rate from tidal interaction is about 3.34 megawatts, the highest rate of tidal orbital decay measured for any natural satellite in the solar system.¹⁶ Modeling of this process suggests that Phobos will not collide with Mars head-on. Instead, tidal stresses will pull it apart before it reaches the surface, likely creating a temporary ring of debris around the planet in a few tens of millions of years.¹⁷ The grooves and fractures already visible on Phobos’ surface may be early signs of this tidal stretching.

This tidal interaction also works in reverse as a scientific tool: by measuring exactly how quickly Phobos is spiraling inward, scientists can infer properties of Mars’ interior, including how deformable the planet is and how it dissipates tidal energy. Mars’ gravity, in this sense, is not just a static number stamped on the planet. It is a dynamic force continually reshaping the planet’s environment, from the dust in its riverbeds to the orbit of its moons.