Metric vs. imperial system explained

If you are an immigrant, chances are that you don't completely understand the imperial system used in the United States. right?

The same is true for tourists. When you are driving your car and the GPS is talking about miles or you go buy a sandwich and the bread is 6-inch size.

Ruler in inches

If that's the case, don't worry because you are not the only one, after living for 5 years in the U.S. I still have a hard time to think in miles, inches, feet, yards and all the units that people use here.

But I have good news for you! 

In this article you will understand how to use the imperial system, it doesn't matter if you don't have any experience with the units, keep reading.

Understanding inches

OK, if you use the metric system it's easy to compare with inches.

Let's start with a tape measure, here is the U.S. most of them come with the scale in centimeters and inches, so you can see that an inch is a little bit more than 2 centimeters. (just practice by looking at the tape measure).

So, if you want to have a quick way to convert from inches to centimeters just type on Google " 1 inch to cm" and you get an immediate conversion.

Google convert 1 inch to cm

That one is easy, isn't it? Believe me, you can learn to think in inches 

You can just use a tape measure to have an idea how long things are and get used to their scope the same way you use to do with centimeters.

The idea is to train your brain to think in inches for small objects, don't compare meters to inches, just compare centimeters to inches, OK?

Some examples with inches measurement

Let's measure a marker

See the picture below. The marker has about 12 cm or almost 5 inches.

Imperial vs metric measurement dry erase

I know... it's a little less than 5 inches, but you got the idea, don't you?

You can learn more later about fractions of an inch, but the main idea here is to compare centimeters to inches. not meters, not kilometers...small stuff. 

Let's measure a remote control

The remote control has about 17 cm or almost 7 inches.

Imperial metric - measuring a remote control

Again... small stuff, if you can measure it in cm, so you can in inches.

On measure more... a mobile

The mobile has about 16 cm or a little bit more than 6 inches.

Imperial Unit measuring a mobile

Understanding the fraction of inches

OK, now that you already understand the idea about inches and centimeters, let's talk about inches fractions. It's pretty easy, don't be scared.

Take a look at the picture below, you can see the inches divisions and between the 2 and 3 inches scale, I'm showing you that there's a 1/2 inch. 

Ruler inches

You can say for example that a pen drive measures 2 and a 1/2 inches and that's is really the size of my pen drive I just measured here πŸ™‚

So... you can say that the pen drive measures 2.5" or 2 1/2"

That was easy. Now let's just divide the scale again, see the next example

One more example with fraction of inches

Take a look at the picture below, you can see that between 2 and 3 inches there are some divisions with different colors specially for you πŸ™‚

Each division represent 1/4 of the total between the 2 and 3, right ?

Reading fraction of an inch

So it's pretty simple I got 3 parts of 4..... so it's 3/4 of an inch.

Now I have 2 entire inches + 3/4 of an inch = 2 3/4"

Exercise with inches measurement

Now it's your turn. Just tell me what the ruler is showing...

C'mon I even let the squares to help you out !

Inches guess

I'm sure you got that right. No need to confirm, I know you are smart !

The inch unit

I think you guessed that inch is represented by the symbol prime ( β€³ )

By convenience people also use the apostrophe ( " )

So, that's why you can see some measurement like 21/2"

Now let's move on to the next one...

Understanding foot

Now that you know inches it's easier to understand foot 

A foot is used to measure things that are a little bit larger. Remember that with the inches you measure small stuff? With the foot, you measure medium stuff, just like you do when using meters instead of using centimeters.

A foot = 12 inches, so if are measuring something that is 12 inches you can say that it's a foot long instead.

And if the thing is larger than 1 foot (12 inches), you have the use the plural of foot which is feet, so something with 24 inches = 2 feet for example.

Example with foot (and feet) measurement

Let's say you are hungry and want to measure a baguette to make sure you are that hungry and can eat it all. You can use foot (or feet) to measure it.

Measuring using feet

You see that now the thing is a little larger and you can start using foot and feet instead of using inches ? Ohh, can't you see the units ? Let's zoom in.

Measuring with feet

The baguette is about 23 1/2" (inches) or almost 2 feet.

Let's just zoom in again so you can see the red mark with 2 feet.

See it? You can click the image to enlarge it if you want to see it better.

2 feet long

(click to enlarge)

So, the baguette is (almost) 2 feet long. Are you sure you can it all? πŸ™‚

Real-life example measurement

So, you are that hungry and go to the next Subway to get a sandwich. 

The lady smiles at you and asks about which bread do you want (Italian, Italian white, wheat, etc) and she also asks how long is the bread you want.

What size options do you have? 6-inch and 12-inch (or footlong) 

Footlong subway

So, you can ask for the footlong if you are really that hungry, right ?

Foot long, footlong or foot-long?

I don't know why some people say foot long, or foot-long or footlong.

This post is not about English grammar, right? So, let just understand the use of the measurement and let grammar to another blog post πŸ™‚

Meanwhile, take a look at this Subway advertisement. Huum, this footlong sandwich should be good, I could eat this 6-inch thing right now πŸ™‚

Footlong sandwitch

So, you can compare foot with meters, however as 1 foot = 0.3 meters we (people that use the metric system) usually still use centimeters in this case. 

If we see something that is 1 foot-long and we convert to the metric system, we tend to say it is 30 cm long instead of 0.3m long, correct ?

Anyway, if we have something that is more than 100 cm large we can measure it using meters or foot (feet), let's say a person for example.

Another real-life example measurement

If somebody asks you, "how tall are you?" What would be your answer ?

Here in the U.S. people usually answer that question in feet and inches.

Exactly the way people in other countries answer the question in m and cm.

Angelna Jolie

How tall is Angelina Jolie?

When asking Google, he tells me she is 5' 7'' tall. But now I know what this means without converting to meters.

So, she is 5-feet and 7-inches tall

If I ask Google to tell me how tall she is in meters, I will get the answer as 1.69 m and I can ask the same question in cm and get 169 cm as the answer for Angelina's height.

My Florida driver license (yeah I have one) says I'm 6' 02"

That means I'm 6 feet and 2 inches tall. ( I'm taller than Angelina, huh ? )

When people ask about my height, I can answer in two different ways:

"I'm six feet and 2-inches tall"

 "I'm six two".

And that's the way you can use foot, feet and inches. It's not that hard πŸ™‚

Understanding Yards

Again, if you want to measure something larger you can use yards.

1 yard = 3 feet ( or 91.44cm or 0.91m )

So, now you have a way to measure intermediate size stuff such as a football field. I bet you've heard somebody screaming something about yards during an important American football game, right?

How long is a football field?

A football field is 360 feet long and 160 feet wide.

You can also say a football field is 120 yards long and 53 yards wide.

Yard it's used in this case because the football field is not large enough so people can use a mile (another imperial system unit).

Do you see the marks in the field? 10 20 30 40 50 and then backward... those are distances and they are represented in yards.

Back to the metric system, when you are watching a Worldcup game, you don't think in kilometers, do you ? It's better to us meters in this case. 

Measurement in meters

So it's basically the same concept for using yards instead of miles.

Understanding Miles

Nice, if you are still reading this, that means you know a lot more about the imperial system and now it's time to talk about miles.

1 mile = 1.6 Km.

This unit is easy, you just need to know that it's a little bit larger than the Km and get used to it to refer to large distances between cities for example.

Here in the United States, miles are used everywhere, 

The GPS can say that the store is located 5 miles away, or you can hear somebody saying that he needs to travel 20 miles to get home.

If the distance is shorter than a mile the GPS still can use this unit by showing 0.5 miles for example as you can see in the following picture.

GPS measures distance in Miles

But the GPS can also speak and say the distances in feet. 

I know because every time I'm driving somewhere and using the GPS she says (Yeah, mine GPS has a girl's voice) "in 300 feet turn right".

Don't worry, if you are an immigrant or a tourist in the U.S. you will get used to the distances while driving your car to some fun place.

You get that feeling of how far is the place after driving for some time. 

Understanding Miles per hour

I got a ticket in the first year I came to us (shame on me).

When I was stopped by a police officer I was a little bit confused with the speed because I used to think in Km/h but in the U.S. the Mph is the king πŸ™‚

1 Mile per hour (Mph) = 1.6  Kilometer per hour (Km/h).

40 Mph speed

Miles per hours not Kilometers per hour. that's the new way to go.

So, I admit I was wrong and speeding a little bit with my Mitsubishi Lancer.

I was running at at 50 Mph and the limit was 40 Mph.

Converting that I get 80 Km/h and 64 Km/h ( I was not that fast).

Anyway I was schooled by the police officer how danger it's to run over the limit, I could hurt myself or somebody else. OK, lesson learned and a ticket πŸ™

Phrases using imperial system

You are reading a lot of material about imperial system, aren't you ?

It's time to recap and see some common phrases used her in the U.S. 

The room is 12 feet wide  (It's not large enough to use miles).

The library is only 2 miles away (Now make sense to use miles).

The garden measures 5 by 10 yards (take good care of it).

I got a 50 inches TV (very common to use inches for TVs).

My new house is 1,200 square feet. (The average size for a house).

I got a ticked because I was running at 50 Mph (And I went to court).

Understanding pounds

Time to think about how to height stuff here in the U.S. Are you ready?

OK, I see you are so excited to learn more about imperial system...

Let's start with the most basic and simple question:

What is pound?

The first time I type that question on Google the first answer were related to a "full body cardio jam session championed by fitness rebels around the world"

Say whaaaat? That's no the pound I was looking for.

Wikipedia has the answer I was looking for "is a unit of mass used in the imperial, United States customary system".

There are still other situation where pound is used, but what we need to know is that pound is a unit that is used in the U.S. to measure height.

1 pound = 0.45 Kg (It's easy to remember because it's almost half a kilo).

When you go yo a supermarket here in the U.S. everything is written in lb.

And lb is the way we write pounds, OK? Take a look at the picture.

Prices per pound in a supermarket

So, when you go to the Walmart to buy fresh vegetables and fruits,  you quickly compare prices by doubling the price to have an estimation in Kg.

In the example about the price is per lb, which means it's S1.47 per 0.45Kg

So, if you want 1 Kg (or 2 lb) you have to pay $2.94. Got it ?

How to weight people?

Want to weight yourself ? Just go to an Publix supermarket in Florida and you will find a weight scale like this on in the picture. I use it sometimes.

I'm about 200 lb (depending on the calendar, because Christmas is tough) πŸ™‚

That's about 90 Kg, not bad for somebody 6' 02" (1.88 m) tall, right ?

Scale at Publix

So, if Angelina Jolie comes to Florida, she can just visit Publix to weight herself and say " I'm 119 pounds" (Yeah... she is about 54 Kg).

Understanding ounces

Another way to weight stuff here in the U.S. is to use ounces.

1 ounce = 28.3495 grams (to weight small stuff decimal number count).

Tomate sauce weight in ounces

Take a close look at the picture of this tomato sauce I got today.

Can you see at bottom left size the Net WT (Net Weight) 15 OZ ?

That's 15 ounces that's about 425g

Every time you buy something you can see the information just like this in this picture.

You can always see how much that represent in grams.

Another way to weight stuff here in the U.S. is to use ounces.

The ounces in a restaurant

When I go to a restaurant here in the U.S. I can see everything weighted in ounces in the menu. So I have to decide if can handle the 4 Oz beef or if it's too much for me. ( Usually I can handle it, I mean... who can't ? ).

Today I was reading an article about protein and there's an interesting information that there's 29 and 36 grams of protein from 4 ounces of cooked beef. The interesting part? The use of ounces and grams in the same phrase.

The ounces is also used for fluid

In the imperial system, fluid is also measured in ounces, it's possible to find bottles that shows the amount of liquid it contains by using the Oz unit.

Usually when you buy a bottle that brings some liquid on it, there's the indication of the quantity in Oz.

As you can see in the bottom left part of the picture, it's also possible to read the information in milliliter (Just click the picture to enlarge it).

Fluid measured in Oz

(click to enlarge)

Understanding Fahrenheit

Right not it's 89ΒΊF here in Miami, I can see that information on the right corner of my TV or on my mobile phone. But it's too hot or too cold ?

At first, you etc go crazy when people say things like that, right?

C'mon, in my native country (Brazil) we use Celsius and everybody would be dead with such temperature. (Thinking about 89ΒΊC).

But in Fahrenheit, this is not that hot. I can say that is warm here in Miami now and my TV just shows me the information also in Celsius. It's 32ΒΊC.

Its hot even in the Celsius scale

The conversion from Fahrenheit to Celsius and vice versa is not that simple and it's necessary to use a formula we've learned years ago in school.

But why waste time calculation if you can just tell your mobile or TV to show the temperature in Celsius and Fahrenheit?

Understanding Gallons

That one is nice. You can go to the gas station and fill the car's tank with just some gallons of gasoline. The first time I did that here in the U.S. I got a good impression on using this unit.

1 gallon = 3.78 liters ( I usually round that to 3.8 to be easier to grasp).

And the gasoline is cheaper here in the U.S. than in Brazil, so I had a really good impression by spending about 40 dollars to fill my car's tank.

Filling the tank and using the GetUpside App

So, with just about 14 gallons the tank is full, that's new to me since I used to use 50 liters to fill the car's tank in Brazil.

I know is the same amount of gasoline but it's nice to use gallons instead of liters, I like it the feeling (and of course the lower price).

And there's an extra tip for people that are living in the U.S. Just read the post about the App to get cashback to fill your car's tank (it's a free App).


If you are an immigrant, student or tourist you can get used to the imperial system and use it everywhere. It's not that easy at first but you can do it.

I hope you have enjoyed this blog post, please share with your friends.

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