Escape Velocity
and Surface Gravity
Scroll down for instructions.

Solving for:  or  or

Do not enter commas.



This calculator can solve for escape velocity, or a gravitational body's mass, radius or surface gravity and will automatically calculate the value of 'g' - the gravitational constant. (For Earth, the value of 'g' is 9.80665 meters per second2.)
You can input a great many different measurements: miles per second, kilometers per second, tons, kilograms, etc.
When using this calculator, always choose what you are solving for first.
Next, from the escape velocity, mass and radius rows, select the units you will be inputting.
Enter the numbers and then click calculate.

1) The planet Mars has a mass of 6.42 x 1023 kilograms and a radius of 3,380 kilometers. What is its escape velocity?
First click on what you are solving for. If you have just loaded the calculator and have not clicked on anything, the default settings are "ESCAPE VELOCITY", "tons" and "miles".
Escape Velocity was chosen by default but you will have to click on "km/sec" and "kilograms" and then enter those two numbers.
NOTE: numbers such as 6.42 x 1023 may be entered as 6.42e23

Click "CALCULATE" and your answers are:
Escape Velocity = 3.13 miles/sec = 5.04 km/sec and
its surface gravity is .382 that of Earth.

2) The planet Mercury's escape velocity is 4.25 kilometers per second and it has a radius of 1,516 miles. What is its mass?
One of the great advantages of an ultra-calculator is that you can enter "mixed units" such as kilometers per second and miles.
First click on what you are solving for which in this case is "Mass".
So, click on the "Mass" and "km/sec" buttons ("miles" was chosen by default). Enter the numbers and your answers are:

Mass = 3.64 x 1020 tons = 3.30 x 1023 kilograms = .055 Earth
and the surface gravity is .377 that of Earth.

3) The planet Venus has an escape velocity of 6.5 miles per second and its mass is 4.87x 1024 kilograms. What is its radius?
Once again we are working with "mixed units", which is not a problem for this calculator. First click on what you are solving for which in this case, is "Radius" then click "kilograms" (miles per second was already chosen). Enter the numbers above and your answers are:

Radius = 3,690 miles = 5,940 kilometers and
the surface gravity is .94 that of Earth.

Significant Figures >>>
Numbers are displayed in scientific notation with the amount of significant figures you specify. For easier readability, numbers between .001 and 1,000 will not be in scientific notation but will still have the same precision.
You may change the number of significant figures displayed by changing the number in the box above.
Most browsers, will display the answers properly but if you are seeing no answers at all, enter a zero in the box above, which will eliminate all formatting but at least you will see the answers.

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