About the G-Force Calculator
This g-force calculator expresses an acceleration as a multiple of standard gravity (1 g = 9.80665 m/s²). Choose how you want to describe the motion — a change of speed over a time (a car launch, braking or a crash), a turn at a given speed and radius (a corner, roller-coaster loop or centrifuge), an aircraft’s bank angle in a level turn, or a known acceleration — and it returns the g-force, the acceleration in m/s², and the apparent weight a person of your chosen mass would feel.
It is useful for physics students learning about acceleration and circular motion, drivers and sim-racers curious about cornering and braking forces, pilots studying load factor, and fans of roller coasters and motorsport. For horizontal motion, the calculator also combines the sideways or forward g with Earth’s 1 g of gravity to show the total load on your body.
Linear mode assumes constant (average) acceleration over the time entered; peak forces in real crashes or launches can be much higher than the average. Turn mode treats the path as a circular arc at constant speed. Bank-angle mode assumes a coordinated, level turn.
With the default inputs, the g-force is 0.944 g. Change any value above to recalculate instantly.
How to use the g-force calculator
- 1Choose how to describe the motion: speed change, turn, bank angle or acceleration.
- 2Select the speed unit and enter the speeds, time, radius or angle.
- 3Enter a body mass to see the apparent weight you would feel.
- 4Read the g-force and the total load including gravity.
- 5Use the chart to see how g-force changes with the main variable.
Formula and method
G-force is acceleration divided by standard gravity g₀ = 9.80665 m/s². For a speed change, the average acceleration is Δv / t. For circular motion at constant speed, the centripetal acceleration toward the centre of the turn is v² / r. Speeds are converted to m/s first (1 km/h = 1/3.6 m/s, 1 mph = 0.44704 m/s, 1 knot = 0.5144 m/s).
In a horizontal manoeuvre you also feel 1 g of gravity pulling down, so the total load on your body is the vector sum √(1 + g²). In a coordinated level turn, an aircraft’s lift must balance gravity and provide the centripetal force, giving a load factor n = 1/cos φ; the turn radius is v² / (g₀ tan φ) and the rate of turn is v / r. Apparent weight is body mass × total g.
- a
- Acceleration (m/s²)
- g₀
- Standard gravity, 9.80665 m/s²
- Δv, t
- Change in speed and time taken
- v, r
- Speed and turn radius
- φ
- Bank angle
- n
- Load factor (g felt in a level banked turn)
Worked examples
Car accelerating 0–100 km/h in 3 seconds
100 km/h is 27.78 m/s, so a = 27.78 / 3 = 9.26 m/s², or 0.944 g pushing you into the seat. Combined with gravity the total load is √(1 + 0.944²) = 1.375 g, so a 75 kg driver feels like 103 kg.
Cornering at 100 km/h on a 50 m radius bend
a = v²/r = 27.78² / 50 = 15.43 m/s², which is 1.57 g sideways — beyond the grip of normal road tyres (roughly 0.8–1 g), so the car would slide.
Aircraft in a 60° bank at 120 knots
The load factor is 1 / cos 60° = 2 g. At 120 knots (61.73 m/s) the turn radius is 61.73² / (9.80665 × tan 60°) = 224 m.
Crash: 50 km/h to a stop in 0.1 s
Losing 13.89 m/s in 0.1 s is an average deceleration of 138.9 m/s², about 14.2 g. Seatbelts and crumple zones lengthen the stopping time to cut this number.
Frequently asked questions
What is 1 g?+
1 g is the acceleration due to standard gravity, 9.80665 m/s². Standing still on Earth you feel 1 g; an acceleration of 19.6 m/s² is 2 g.
How do you calculate g-force?+
Divide the acceleration in m/s² by 9.80665. For a speed change, acceleration = change in speed ÷ time; for a turn, acceleration = speed² ÷ radius.
How many g can a human withstand?+
Tolerance depends on direction and duration. Untrained people often lose vision around 4–6 g of sustained head-to-foot load; fighter pilots with g-suits and training sustain about 9 g. Very brief impacts can be survived at much higher values.
What is load factor in a banked turn?+
In a level, coordinated turn the load factor is 1/cos(bank angle): 1.15 g at 30°, 1.41 g at 45°, 2 g at 60°. Stall speed increases with the square root of the load factor.
Why does braking feel stronger than the g-force number?+
The number shown is the average over the time entered. Real braking or impacts often have short peaks above the average, and your body also feels gravity at the same time, which is why the total g is shown too.