Car Crash Calculator

Your details

A seatbelt roughly quintuples the stopping distance (about 20 cm instead of 4 cm), spreading deceleration over more time and dramatically reducing impact force. Choose Custom to enter your own stopping distance or time.
Use stopping distance (the crumple zone / seatbelt stretch) or stopping time (how long deceleration lasts). Both give the same result if consistent.
The speed of the vehicle just before impact.
km/h
Your body weight (the moving mass that must be decelerated).
kg
The distance over which the passenger decelerates. Used only when Seatbelt is set to Custom - the presets use 20 cm with a seatbelt (belt stretches + airbag) and 4 cm without (body hits dashboard).
m
Impact forceHigh G-force
36,169

Average force during the collision

Impact force (display unit)36.17 kN
G-force49.2g
Deceleration482.3m/s²
Stopping time28.8ms
Kinetic energy7.23kJ
Feels like being pressed by3,688
Equivalent mass (display)3688 kg
49.2 g
Low<10Moderate10-30High30-60Extreme60+

Impact force is 36.17 kN (49.2 g) at 50 km/h.

  • At 50 km/h, the deceleration produces about 49.2 g. Over a 20 cm belted ride-down the same crash is about 49 g; over the 4 cm an unbelted body gets, it is about 246 g.
  • A seatbelt stretches and distributes deceleration over about 20 cm instead of 4 cm. Because average force is inversely proportional to stopping distance, that is roughly a 5-fold cut in peak force compared with no restraint.
  • NHTSA data show that seatbelts reduce crash fatality risk by 45% and the risk of serious injury by 50%.

Next stepToggle to "No seatbelt" to see how much the impact force rises when the stopping distance shrinks to 4 cm.

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