# Why Do We Use MPH?

The Hot Stove is still pre-heating, so while we wait on the oven timer, let’s reflect on a topic that we rarely question. Provocative title aside, why do we use miles per hour, more commonly referred to as mph, to talk about velocity in baseball? After all, it’s a game of feet, inches, and seconds.

It’s 60 *feet*, six *inches* from the rubber to the back corner of the plate. Home to first is 90 *feet*. Home to second is 127 *feet*, three and 3/8’s* inches*, which can also be expressed as 90 times the square root of two (h/t Pythagoras). The outfield fence is typically somewhere between 310 and 410 *feet* from home plate. A really long home run will travel 500 *feet* in about four to six *seconds*. Billy Hamilton can steal second base in 3.1 *seconds*. When Jose Fernandez hits a home run, it takes him about 28* seconds* to wander around the bases.

In other words, no other single activity in baseball is meaningfully measured using miles or hours.

A simple googling of the topic reveals nothing helpful. In fact, the search phrase “why does baseball use miles per hour?” *never appears*. Tinkering with that search phrase reveals very little useful information.

We can intuit that the widespread use of mph in baseball has much to do with available technology. Radar guns, which were invented in the late 1940s, are still the primary method for measuring pitch velocity. According to Wikipedia, they were originally invented for military purposes, but the most popular application of the technology is to measure the velocity of cars. You knew that.

Baseball Reference traces the origins of the radar gun in baseball to the 1960s. Danny Litwhiler and John Paulson invented the JUGS gun in 1974, which measures pitch velocity from when the ball leaves the pitcher’s hand. It is still the gun of choice today.

We can guess why the first guns used mph, but it’s harder to understand why it has remained the unit of measurement for pitch velocity. When Justin Verlander follows a 95 mph fastball with a 98 mph fastball, we know that he’s throwing gas, but it’s not obvious how the hitter’s reaction time is affected. If Verlander were then relieved by Jamie Moyer‘s 78 mph fastball, how much more time would a hitter have to react?

It would seemingly be more intuitive to use feet per second (ft/s) as these are units that translate directly to the activities on a baseball diamond. Below is a conversion from mph to ft/s with time to plate added for fun.

**The time to plate column is based on 60 feet, six inches for simplicity and uniformity. To accurately measure time to plate requires knowledge of the exact release point of each pitch, which is generally between 52 and 55 feet. It’s also worth noting that the velocity diminishes fairly rapidly once the ball is released, so actual pitches will take slightly longer to travel 60 feet.*

As you can see, one mph equates to about 1.467 ft/s. Put another way, 15 mph equals 22 ft/s.

Ostensibly, those of you out in Readerland are waiting for an explanation as to why the above chart is groundbreaking. Well, it’s not. In fact, ft/s is scarcely more intuitive than mph. Let’s face it, if ft/s was a groundbreaking change, saberists would have been all over it years ago.

There are, however, a couple simple advantages to ft/s. The relationship between velocity and reaction time is immediately obvious. Anyone can take 60 feet, mentally divide by the observed ft/s, and have a rough estimate of how much time the batter had to hit the pitch.

The measure also allows for slightly greater precision, but that is of dubious value. Besides, anyone analyzing PITCHf/x or Trackman data will have precise information regardless of the unit of measure.

It’s generally accepted that a one mph increase in velocity results in fewer runs allowed. Combining these results with the above chart shows that a hitter’s ability can be strongly disrupted by a pitch that travels only a few thousandths of a second faster than the previous pitch. Hitters are already operating at the extremes of a human’s ability to accurately track and interact with an object in flight, and even the most marginal of changes could tip the scales in favor of the pitcher. For example, the difference between a 98 mph Verlander fastball and Moyer’s 78 mph slowball is just a single tenth of a second.

The chart also tells us why there has never been a groundswell to convert from mph to ft/s. Most baseball fans learn the relationship between an impressive pitch and its velocity pretty quickly. Announcers are usually capable of filling in the gaps for more casual fans. Thinking in thousandths of seconds remains an esoteric concept for most people, so being able to immediately convert velocity to a rough measure of reaction time has no practical purpose.

All told, it’s hard to dispute that ft/s is qualitatively more useful to a baseball fan. You can intuit more information from ft/s, however the value of that information remains limited. The time to make the change was probably back in the 1970’s, shortly after the JUGS gun was invented. Today, a change would require an uphill battle against tradition. Simply put, it is not worth the effort.

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I think the most obvious reason for using MPH is that it seems the speed limit of human ability to throw a baseball sits around 100. That is a nice even number that people can comfortably latch on to.

Is that actually a “reason?”

Note that cricket bowling speeds are also given in mph or km/h. Never seen them given in ft/s or m/s numbers.

As good a reason as having a volume knob top out at “10”

My volume knob goes to 11, so I guess mine is 1 louder.

This doesn’t make sense. Why not just set the 10 so it’s that loud?

These go to eleven

Eleven, eleven, eleven. 11.

Also, 150 ft/s is quite close to 100 mph, so you still have a nice round number to target as “extreme”

Yes, but ft/s is simply not used nearly as commonly in life. (Nor is m/s.) Certainly if we used ft/s exclusively for pitches, we’d easily be able to compare pitches to each other. But we wouldn’t be able to compare them to the speed of other things as easily.

Now, sometimes adding another unit is justified when the common unit yields strange or inconvenient numbers (such as the use of Celsius over Kelvin for air temperatures even in otherwise SI countries, or even the preference for the non-SI liter, aka cubic decimeter, over multiples of cubic meters.) That leads to the use of all sorts of specialized and customary units (barrels of oil, etc.); using ft/s would be the same sort of special pleading. However, as noted above, that doesn’t apply here– mph gives perfectly normal easy to comprehend numbers that can be compared with the speeds of other objects quite easily.

The argument is:

1) Prefer the most commonly used unit.

2) If the particular use commonly measures magnitudes are are inconvenient in the common unit, consider a specialized unit.

The argument that ft/s or yd/s has just as convenient numbers is irrelevant since mph (and km/h) are more commonly used. Hence why cricket also uses mph and km/h for bowling.

ft/s is not used in daily life because it’s a ridiculous unit of measure. The whole world* (minus a couple places) uses m/s (or km/h, but don’t get me started on the whole 60s/min, 60min/h stupidity that sweeps the globe).

The only reason why we use MPH is because we still use it in cars and driving, so we have some frame of reference for it. If we dropped that, how much does anyone in the US use ANY unit of measure for speed? Or distance, for that matter.

B N

Time is based on the idea of splitting up the sphere (which has 360 degrees) equally for ocean travel. So while it would be nice if we would have said a sphere has 100 degrees… they didn’t and thus time still works good for everyone.

“thus time still works good for everyone”

Unless you went somewhere other than earth where hours are downright useless (e.g., Try to tell an alien how far away you are in light years… might as well say something weighs 10 pounds).

The fact is, we’re still using a time system that was designed based its ease for making sundials and computing fractions without decimals. While I salute their longevity, that’s a fairly crazy thing.

My car gets 40 rods to the hogshead and that’s the way I likes it