Is 2.54 cm exactly 1 inch? Or maybe 2.54 cm is only an approximation of 1 inch? How does the relationship between these 2 units look? If these are questions to which you want to get answers, you are in the right place. Let’s dispel all doubts once and for all.
Is 1 inch exactly 2.54 cm? This is one of the most commonly asked questions by people who are used to using the Imperial system of measurement or the US customary system of measurement. It means it is often asked by people from the UK and the US. And it is understandable because an inch and a centimeter are significantly different.
So let’s see the difference between an inch and a cm, and know if 2.54 cm is exactly 1 inch or not.
What is the definition of an inch? It is needed to emphasize that an inch is a quite specific unit when it comes to the definition. Why? This unit can’t be defined descriptively. An inch is defined only using an accurate value.
Formerly, an inch has its own legal, descriptive definition. To be honest, a few versions of it. But the most commonly used was the definition in which an inch was compared to the length of 3 barleycorns. As you may know, a definition like this was so inaccurate. Using this definition caused many mistakes. That’s why people have stopped using it.
The next definition of an inch used nowadays compares an inch to another unit of length – the millimeter. This is the unit from the metric systems, in a full name also called the International System of Units (in abbreviation the SI).
So how does the definition of an inch look nowadays? In comparison to the millimeters an inch is defined as follows:
As you can see, the millimeters are so much smaller than 1 inch. But how does it look when it comes to centimeters? Let’s check it.
To know how many centimeters in an inch exactly, it is needed to convert the millimeters to centimeters. How to make it?
You need to know how many millimeters are in 1 centimeter. Thanks to this knowledge you will be able to make a conversion. So, in 1 centimeter is exactly 10 millimeters:
So how to calculate 25.4 mm to cm? You need to divide the number of millimeters by 10. Then you will have the result in centimeters.
It is not a complicated calculation. To be honest, you don’t even need to calculate it. How is it possible? To convert millimeters to centimeters you need to only move a comma one place to the left. Simple, right?
So let’s see how it looks in practice:
25.4 millimeters / 10 (move a comma one place to the left) = 2.54 centimeters
We said before that 1 inch is defined as 25.4 millimeters. Above we showed you how to calculate this number of millimeters to centimeters. Thanks to this you know now that 1 inch is equal to 2.54 centimeters:
So what do you think? Is 2.54 cm exactly 1 inch? Or maybe is this result rounded off? We are going to dispel all your doubts down below. Check it to know an accurate answer.
Let’s make a quick analysis. An inch is defined exactly as 25.4 millimeters. This information you can take for granted.
The next thing which you need to analyze is if 1 centimeter is exactly 10 millimeters. And the answer is yes. It is an exact result, not an approximation.
So due to this fact it means that also 25.4 millimeters are exactly 2.54 centimeters.
And if 2.54 centimeters are 25.4 millimeters exactly, it means 2.54 centimeters are 1 inch exactly.
So, to sum up, there are 2.54 cm in 1 inch exactly.
Have a look at the equation too:
1 inch = 25.4 millimeters = 2.54 centimeters
Is 1 inch exactly 2.54 cm? We hope you can answer this question without any trouble now. If you need a reminder, here it is:
Do you want to know more about an inch? Let’s check how an inch is defined and know its equivalents in other units than millimeters and centimeters.