Neptune is the smallest of the gas giants in the Solar system. And yet, it is considerably bigger than Earth. It is so big that you could fit 57 Earth-sized planets into it.

With that in mind, Neptune’s gravity should be much stronger, right?

Well, you might be surprised to know that that’s not the case. Neptune’s gravity is only 13% stronger than Earth’s. Why is that the case?

Well, the answer is that the mass of the gas planets is distributed across a greater volume, and as a result, these planets have very low density, and therefore, a lower gravitational acceleration. As a result, even though the mass of these planets is much greater than Earth’s, their gravity doesn’t increase at the same rate.

So, how much would you weigh on Neptune?

Below you will find a calculator that can answer that for you with precision. But before we get to that there’s something that must be clarified.

A person can’t stand on Neptune because the planet is made out of gas. It does not have a solid surface to walk on. If you were to “fall” into the planet, you would sink all the way into its core. There would be nothing would stop you. Well, that is except for the low temperatures, crushing pressure, supersonic winds, and toxic atmosphere that would destroy you long before you could reach the core but let’s say you had a way to survive all that.

For the purpose of this exercise then, if you wanted to calculate how much would you weigh on Neptune, we will need to imagine that the planet does somehow have a solid surface. Now that that’s cleared up, let’s proceed.

In this imaginary Neptune-like planet, you would weigh approximately 13% more than your current weight on Earth. A person who weighs 70 kilograms (154 lbs) on Earth would weigh approximately 79.5 kilograms (175 lbs) on Neptune.

On top of that, to walk on this imaginary version of Neptune, you would have to add up the weight of the spacesuit required to survive.

To give you an idea of how heavy astronaut suits are, the spacesuits that the Apollo astronauts used to walk on the Moon weighed about 163 kilograms (360 pounds) on Earth. On the Moon that weight was reduced to just 27 kilograms (60 pounds) which is still a lot, but it is manageable. On Neptune, the weight of this equipment would be even greater, making it much harder to carry around.

To precisely calculate your weight on Neptune, you can use a simple rule of three that factors in the difference between the force of gravity on both planets.

The following calculator simplifies the process.

Weight on Neptune calculator

If you want to skip the calculation, just fill out the following calculator. The dropdown lets you switch between kilograms and pounds.

Click “calculate” to get the result below.

Weight on Neptune formula

The formula to calculate your weight on Neptune is as follows:

WNeptune = (WEarth / 9.81) * 11.15

WNeptune: Weight on Neptune

WEarth: Weight on Earth

The other two numbers are the force of gravity on each planet and it is given in meters per square second (m/s2). The force of gravity on Earth is 9.81 m/s2 and on Neptune, it is approximately 11.15 m/s2.


Elena is a Canadian journalist and researcher. She has been looking at the sky for years and hopes to introduce more people to the wonderful hobby that is astronomy.