Accurate physics calculator to determine weight based on mass and gravitational acceleration.
Kilograms (kg)
Pounds (lb)
Grams (g)
Enter the mass of the object.
Please enter a valid positive mass.
Earth (Standard) – 9.81 m/s²
Moon – 1.62 m/s²
Mars – 3.71 m/s²
Jupiter – 24.79 m/s²
Venus – 8.87 m/s²
Mercury – 3.70 m/s²
Saturn – 10.44 m/s²
Uranus – 8.69 m/s²
Neptune – 11.15 m/s²
Sun – 274 m/s²
Zero Gravity (Space) – 0 m/s²
Custom Acceleration…
Select a celestial body or enter a custom acceleration.
Calculated Weight (Force)
686.47 N
Formula: Weight = Mass × Gravity
Mass in kg
70.00 kg
Acceleration (g)
9.81 m/s²
Weight in kgf
70.00 kgf
Weight in lbf
154.32 lbf
Weight Comparison Across Solar System
Comparison of weight for the input mass across different celestial bodies.
Location
Gravity (m/s²)
Weight (Newtons)
Relative to Earth
What is Calculate Weight by Force of Gravity?
To calculate weight by force of gravity is to determine the gravitational force exerted on an object based on its mass and the acceleration due to gravity in its current environment. In physics and engineering, it is crucial to distinguish between mass and weight. While mass represents the amount of matter in an object and remains constant regardless of location, weight is a force that changes depending on the strength of the local gravitational field.
This calculation is fundamental in fields ranging from aerospace engineering to structural design and general physics education. Using a dedicated tool to calculate weight by force of gravity ensures precision, especially when dealing with varying gravitational environments like different planets or varying altitudes on Earth.
A common misconception is that mass and weight are the same. In everyday language, we often use "kilograms" or "pounds" to refer to both. However, scientifically, kilograms measure mass, while Newtons (N) or pounds-force (lbf) measure the weight generated by gravity acting on that mass.
Weight Formula and Mathematical Explanation
The process to calculate weight by force of gravity relies on Newton's Second Law of Motion. The primary formula used is:
W = m × g
Where:
Variable
Meaning
Standard Unit (SI)
Typical Range
W
Weight (Force)
Newtons (N)
0 to ∞
m
Mass
Kilograms (kg)
> 0
g
Acceleration due to Gravity
Meters per second squared (m/s²)
9.81 (Earth), 1.62 (Moon)
To perform the calculation accurately, all units must be consistent. If mass is given in pounds, it should typically be converted to kilograms before using the standard metric formula, or used with the Imperial gravitational constant (32.174 ft/s²) to find weight in slugs or pounds-force.
Practical Examples (Real-World Use Cases)
Example 1: An Astronaut on the Moon
Suppose an astronaut has a mass of 80 kg. To calculate weight by force of gravity on the Moon:
Mass (m): 80 kg
Gravity (g): 1.62 m/s² (Moon)
Calculation: W = 80 × 1.62
Result: 129.6 Newtons
Comparatively, on Earth (g ≈ 9.81 m/s²), the same astronaut would weigh 784.8 Newtons. This explains why astronauts can leap high on the Moon despite having the same body mass.
Example 2: Heavy Machinery on Mars
A Mars rover has a mass of 1,025 kg. Engineers must calculate weight by force of gravity to design the landing gear.
Mass (m): 1,025 kg
Gravity (g): 3.71 m/s² (Mars)
Calculation: W = 1025 × 3.71
Result: 3,802.75 Newtons
On Earth, this rover would weigh over 10,000 Newtons. The reduced weight on Mars allows for different suspension requirements compared to Earth-based vehicles.
How to Use This Calculator
Enter Mass: Input the mass of the object in the "Mass" field. Ensure you select the correct unit (kg, lb, or g) from the dropdown.
Select Environment: Choose a celestial body from the "Gravitational Environment" list (e.g., Earth, Moon, Mars).
Custom Gravity: If you need to calculate for a specific altitude or a theoretical planet, select "Custom Acceleration" and enter the specific g value.
Review Results: The tool will instantly calculate weight by force of gravity and display the result in Newtons, kg-force, and lb-force.
Analyze Data: Check the dynamic chart and table to see how the weight of your object compares across the solar system.
Key Factors That Affect Weight Calculation
When you calculate weight by force of gravity, several factors influence the final "g" value and thus the weight:
Planet Mass: Larger planets with more mass typically have higher gravitational pull (e.g., Jupiter).
Planet Radius: Gravity weakens with distance from the center of mass. A larger radius can offset a large mass (e.g., Saturn has lower surface gravity than expected due to its low density and large size).
Altitude: On Earth, gravity decreases as you go higher. An object weighs slightly less at the top of Mount Everest than at sea level.
Latitude: Earth is not a perfect sphere; it bulges at the equator. Consequently, gravity is slightly stronger at the poles than at the equator.
Local Geology: Variations in the density of Earth's crust (mountains vs. ocean trenches) can cause minute anomalies in local gravity.
Buoyancy (Atmosphere): While not strictly gravitational, the buoyant force of the atmosphere can slightly offset the measured weight on a scale, though the gravitational force itself remains unchanged.
Frequently Asked Questions (FAQ)
1. Why is weight different on other planets?
Weight depends on the local acceleration due to gravity. Since other planets have different masses and radii, they exert different gravitational forces on the same mass.
2. Does mass change when I go to space?
No. Mass is the measure of matter in an object and remains constant. Only the weight changes as gravity changes.
3. How do I convert Mass to Weight?
Multiply the mass (in kg) by the local gravity (in m/s²). The result is weight in Newtons.
4. What is the standard gravity on Earth?
Standard gravity is approximately 9.80665 m/s². This calculator uses 9.81 m/s² for simplicity unless "Custom" is specified.
5. Can I use this to calculate weight by force of gravity for structural engineering?
Yes, this tool provides accurate force calculations (Newtons) required for load analysis, assuming standard static conditions.
6. What is kgf (kilogram-force)?
Kgf is a non-SI unit of force. 1 kgf is the force exerted by gravity on 1 kg of mass on Earth. It is approximately equal to 9.81 Newtons.
7. Why is the result in Newtons?
The Newton (N) is the standard scientific unit for force (and weight) in the International System of Units (SI).
8. Is weight zero in space?
In deep space far from massive bodies, gravity approaches zero, so weight approaches zero. In orbit (like the ISS), astronauts are in "free fall," creating the sensation of weightlessness, though gravity is still acting on them.