100 mph to km/h

100 mph is 160.93 km/h. The exact figure is 160.934 km/h: 100 × 1.609344 = 160.934. The converter above starts at 100 mph; change it to convert any other speed, or use the full mph to km/h converter.

What is 100 mph in other units?

At 100 mph you travel 44.7 meters, nearly half a soccer pitch, every second. A one-second glance away from the road at that speed is the length of about ten cars.

100 mph to km/h chart (80–120 mph)

Computed with km/h = mph × 1.609344, rounded to two decimals, using the same code as the converter.

Is 100 mph legal anywhere in the US?

No. The fastest posted limit in the United States is 85 mph (136.79 km/h), on a 41-mile toll section of State Highway 130 between Austin and Seguin, Texas. The Texas Transportation Commission approved it in September 2012, reported the Texas Tribune; Texas law allows 85 mph only where a road is designed for it and an engineering study finds it safe. Most other US limits top out at 70–80 mph (112.65–128.75 km/h).

So 100 mph is at least 15 mph (24.14 km/h) over any US limit. The IIHS speed-limit table shows nine states (Idaho, Montana, Nevada, North Dakota, Oklahoma, South Dakota, Texas, Utah and Wyoming) post 80 mph on at least some roads, and only Texas posts 85 mph.

Is 100 mph fast, and is it safe?

100 mph is very fast for a road vehicle and is not safe on a public road. At 44.7 m every second, a driver who takes one second to react has travelled almost half a football field before the brakes do anything. The Insurance Institute for Highway Safety explains why speed matters twice: high speeds make a crash more likely because drivers have less time to react, and they make collisions more deadly because modest increases in speed cause large increases in crash energy. In 2024, 11,288 people, 29% of all US motor vehicle deaths, died in speed-related crashes, according to IIHS.

Crash energy rises with the square of speed, so at 100 mph a car carries about 2.0 times the energy it has at 70 mph (100² ÷ 70² = 2.04), and 1.4 times the energy at the 85 mph Texas maximum (100² ÷ 85² = 1.38). That is the arithmetic behind “is 100 mph too fast”: on a road built and signed for 70–75 mph, it is.

How fast is 100 mph for a train?

On US railroads, 100 mph is a passenger-train speed that needs Class 6 track. Federal track-safety rules set the maximum operating speed by track class: 49 CFR 213.9 caps passenger trains at 90 mph (144.84 km/h) on Class 5 track, and 49 CFR 213.307 adds the high-speed classes:

In km/h countries the common equivalent is 160 km/h, which is 99.42 mph, just under 100 mph. Our guides to how fast trains go and the fastest trains in the world put these numbers next to real services.

How does 100 mph compare with other speeds?

100 mph sits between the fastest road cars are allowed to go and the slowest high-speed trains. Each figure below comes from a sourced page on this site and is converted exactly:

Sources and context: how fast a human can run, how fast trains go and how fast planes fly.

How long does a trip take at 100 mph?

Use the speed, distance and time calculator for any other trip.

How do I convert 100 mph to km/h in my head?

• × 1.6: 100 × 1.6 = 160 km/h, about 0.6% low.
• Add 60%: 100 + 60 = 160 km/h.
• Exact: 160.934 km/h. The reverse, 160 km/h, is 99.42 mph.

Can a phone measure 100 mph accurately?

Yes, GPS speed works at any road or rail speed, but treat it as an estimate. Our GPS speedometer reads speed from your phone’s GPS Doppler data, which is accurate on an open-sky train or as a passenger, and less reliable in tunnels and deep cuttings. It is for information only, not legal evidence. Never handle a phone while driving.

Related conversions

• 120 km/h to mph: 74.56 mph
• 60 mph to km/h: 96.56 km/h
• Speed converter: mph, km/h, knots, m/s and Mach