At What Speed Does a Car Crash Become Fatal?
Quick answer: for a pedestrian hit by a car, the risk of death rises steeply with impact speed. US research (Tefft 2011) puts it at 10% at 23 mph, 50% at 42 mph and 90% at 58 mph; German research (Rosén & Sander 2009) at about 8% at 50 km/h (31 mph) and 50% at about 75 km/h (47 mph). Older people face much higher risks at the same speed. For belted car occupants the survivable range is higher, but risk climbs quickly beyond about 40 mph.
Updated · formulas checked against the sources below
Default shown: impact at 50 km/h (31 mph). Change the speed or age above.
These are population averages from crash research, not a prediction for any one person. Real outcomes depend on the car's front shape, where the person is hit, how they land, their age and health, and how quickly they reach trauma care. Not a substitute for an accident reconstruction or medical expert.
The published pedestrian risk curves
Rosén and Sander (2009), German in-depth crash data
Erik Rosén and Ulrich Sander fitted a logistic curve to pedestrians aged 15 and over hit by the front of a car, from the German In-Depth Accident Study (GIDAS), weighted to correct for the over-sampling of severe crashes. Their published formulas, with v the impact speed in km/h:
Worked example: at 50 km/h, 6.9 − 0.090 × 50 = 2.4, and 1 ÷ (1 + e^2.4) = 1 ÷ 12.0 ≈ 8.3%. At 30 km/h the same formula gives 1.5%, so the 50 km/h risk is more than five times higher. The authors stress that the curve describes Germany, and that risks would probably be higher where emergency care is less developed.
Tefft (2011), AAA Foundation for Traffic Safety, US data
Brian Tefft analysed US pedestrian crashes from 1994-1998, standardised to the 2007-2009 US pedestrian population. The average pedestrian's risk of death reaches:
- 10% at 23 mph (37 km/h)
- 25% at 32 mph (51 km/h)
- 50% at 42 mph (68 km/h)
- 75% at 50 mph (80 km/h)
- 90% at 58 mph (93 km/h)
The same report gives a separate curve for severe injury or death, which reaches 10% at 16 mph and 50% at 31 mph. The calculator reads the death curve between the five published points in a straight line; outside 23-58 mph it only says "under 10%" or "over 90%".
Pedestrian risk of death by impact speed
Calculated from the Rosén & Sander (2009) formulas above (pedestrians aged 15+, German data). The last column reads Tefft's (2011) US death curve between its published points, for the average pedestrian.
| Impact speed | All ages 15+ | Age 30 | Age 50 | Age 70 | Tefft (US) |
|---|---|---|---|---|---|
| 20 km/h (12 mph) | 0.6% | 0.2% | 0.5% | 1.2% | under 10% |
| 30 km/h (19 mph) | 1.5% | 0.6% | 1.4% | 3.1% | under 10% |
| 40 km/h (25 mph) | 3.6% | 1.6% | 3.6% | 7.6% | about 13% |
| 50 km/h (31 mph) | 8.3% | 4.1% | 8.7% | 17.5% | about 23% |
| 60 km/h (37 mph) | 18.2% | 10.0% | 19.8% | 35.4% | about 38% |
| 70 km/h (43 mph) | 35.4% | 22.3% | 38.9% | 58.7% | about 55% |
| 80 km/h (50 mph) | 57.4% | 42.6% | 62.2% | 78.6% | about 74% |
| 90 km/h (56 mph) | 76.9% | 65.7% | 81.0% | 90.5% | about 86% |
| 100 km/h (62 mph) | 89.1% | 83.2% | 91.7% | 96.1% | over 90% |
The two studies disagree most at middle speeds: at 40 mph Tefft's US average is about 45%, while Rosén & Sander's German formula gives about 25%. Both agree that risk climbs steeply between 30 and 40 mph (50 and 65 km/h). The World Health Organization puts it this way: the risk of death for pedestrians hit by car fronts rises 4.5 times from 50 km/h to 65 km/h.
What speed means for drivers and passengers
There is no simple published "risk of death by speed" curve for car occupants that fits every crash, because the outcome depends on the type of crash (frontal, side, rollover), the change of speed in the crash rather than the travelling speed, the car's design and whether people wore belts. A few points are solid:
- Small speed changes matter. The WHO states that every 1% increase in mean speed produces a 4% increase in fatal crash risk.
- Crash tests show the designed limit. NHTSA's frontal test crashes a car into a rigid barrier at 35 mph and the IIHS frontal overlap tests run at 40 mph. A belted adult in a well-rated car is expected to survive these; crashes well above them use up the crumple zone. See crash test ratings.
- Side impacts are worse at the same speed because there is only a door and some padding between the other car and the occupant.
- Energy grows with the square of speed. A crash at 60 mph carries four times the energy of one at 30 mph; the crash force calculator shows the G-forces and the equivalent fall height (a 30 mph crash is like falling about three storeys).
- Belts. An unbelted occupant keeps moving at the car's original speed and stops against the interior in a few centimetres, which multiplies the force many times over.
Crash speed and survival — FAQ
At what speed does a car crash become fatal?
What speed is a pedestrian likely to survive?
Why do the two studies give different numbers?
Does age change the risk?
Is a head-on crash at 50 mph like hitting a wall at 100 mph?
Sources and method
- Rosén, E. and Sander, U. (2009). Pedestrian fatality risk as a function of car impact speed. Accident Analysis and Prevention 41, 536-542 — equations (2) and (3), used as published; author preprint hosted by NACTO
- Tefft, B. C. (2011). Impact Speed and a Pedestrian's Risk of Severe Injury or Death. AAA Foundation for Traffic Safety — the five death-risk points and the severe-injury points quoted above
- World Health Organization: Road traffic injuries fact sheet — 1% mean speed → 4% fatal crash risk; pedestrian risk 4.5 times from 50 to 65 km/h
- NHTSA: 5-Star Safety Ratings — frontal test speed
- IIHS: About our crash tests — frontal overlap test speed
Method: Rosén & Sander formulas computed exactly as published (v in km/h; mph × 1.609344). The Tefft value is a straight-line reading between the five published points, labelled as such; we do not reproduce the report's tables. The calculator runs in your browser. Checked 2026-11-02.