Who invented the three-point seat belt?

By Kitson Workshop · 3 October 2026 · 6 minute read

Short answer: the Swedish engineer Nils Bohlin designed the three-point seat belt that Volvo put into its cars in 1959. But he did not invent the seat belt itself. Volvo Group says belts had existed "in one form or another" long before, since the mid-nineteenth century, and that a new belt prototype was handed to Bohlin, who perfected it. What he got right was less about the strap and more about where it is fixed.

From aircraft to cars

Bohlin was born in Sweden in 1920 and trained as a mechanical engineer. According to Lemelson-MIT, he joined Saab in 1942 as an aircraft designer, working on pilot rescue systems. In 1958 Volvo hired him as a safety engineer. Lemelson-MIT says he spent about a year on the design: one strap across the chest, one across the hips, joined beside the hip, holding both the upper and lower body, and fastened with one hand. Volvo introduced it in 1959, at first in cars for its home market. By 1963 every Volvo came with front seat belts.

Volvo also let every carmaker use the design free of charge. In 1967 Bohlin presented a study of 28,000 accidents, which Lemelson-MIT says helped inspire an American law requiring three-point belts in the front seats of passenger cars.

What was wrong with the belts before?

The most common belt of the time, Lemelson-MIT says, was a single lap strap with the buckle over the stomach. It held your hips but nothing held your chest, and in high-speed crashes the buckle could injure the organs beneath it.

Some belts already had a chest strap and a hip strap. The problem was what they were attached to. Bohlin's own patent (US 3,043,625) explains that those belts passed much of the load into the back of the seat and pushed down on the spine. In a crash the seat back could bend forward, or the whole seat could come loose from its fixings. The belt was only ever as strong as the seat.

The insight: fix the belt to the car, not the seat

The patent puts three mountings on the car's body: one at shoulder height, behind and to one side of you, and one on the floor on each side of the seat. The chest strap and lap strap form one continuous sling that meets in a single buckle, low down by your hip. The patent says the belt's pull isn't passed to the seat at all; the car's body and floor take it.

Then there is where it holds you. The Insurance Institute for Highway Safety (IIHS) says belts are designed to spread crash forces across the stronger, bony parts of the body: the shoulder, the rib cage and the pelvis. The lap part sits low on the hips, not the belly, and the shoulder part crosses the middle of the chest. Two straps make a V, and the load goes into bone.

Finally, the patent stresses that the belt is easy to fasten and unfasten with a simple hand movement. A safety device only works if people actually use it.

Why a belt works at all

When a car hits something, it stops fast, but you don't. IIHS puts it plainly: unbelted people keep moving at the same speed until they hit whatever is in front of them, a second collision. A belt ties you to the car so you slow down with it while the front of the car crumples and soaks up energy. The longer you "ride down" a crash, the less likely you are to be hurt.

What the numbers say (read carefully)

Note what each number covers. The US figures are for every kind of seat belt, not only Bohlin's design. The million-lives figure is Volvo's own. And one sobering point from IIHS: nearly half of the people who die in crashes are not belted.

Four lessons for engineers today

1. Design for real people. The one-hand buckle mattered as much as the strength of the strap.
2. Follow the load path. Ask where the force really goes, and send it into something built to take it.
3. Question the anchor, not just the part. The weak point wasn't the strap; it was what the strap was fixed to.
4. Openness multiplies impact. When a safety design is free to use, nobody has to wait for permission to fit it.

Sources

• Lemelson-MIT: Nils Bohlin
• Volvo Group: the three-point safety belt
• US patent 3,043,625
• IIHS: seat belts
• CDC: seat belt facts

Sources were checked on 3 October 2026 for our video on Bohlin.

For educational purposes only: not engineering, legal or safety advice. Volvo, Saab and the other organisations named have not made, sponsored or endorsed this article.