How to Measure A Laptop Size for A Bag: A Detailed Tutorial

If you’re looking to buy a new laptop bag from online stores or sew your own laptop case, the first thing you need to know is the size of your laptop.

It’s important for you to know how to measure a laptop size for a bag because you don’t want to waste your money on buying the wrong size of a laptop bag that later cannot fit for your device.

The best way to measure to laptop your actual laptop size is by measuring diagonally across the laptop with your tape. The measurement is including the bezel, the casing that surrounds the screen.

So, how do you measuring your laptop?

In this tutorial, I’ll show you step by step on how to measure a laptop size for a bag so that you can always choose the right size bag for your laptop.

Things to Know Before Measuring Your Laptop

First thing first, before you start to measure your laptop, you need a measuring tape or ruler. Secondly, of course, your laptop.

In this tutorial, I assume that you already know how to read the measuring units on your tape. 

The standard measurement unit that we use is in inches. However, some people like to measure it in centimeters. 

It doesn’t matter which one do you choose, but for this tutorial, all my measurements are in inches.

The scale factor of inches on your measuring tape is 1:8. For example:
1.0″, 1.1″, 1.2″, 1.3″, 1.4″, 1.5″, 1.6″, 1.7″, 2.0″, 2.1″,……

You can use the calculator below if you need to convert it in centimeters.

Now let’s get started!

How to Measure A Laptop Size for Bag

As mentioned earlier, the ideal way to measure your laptop size is by measuring diagonally across the laptop; edge to edge. 

However, you also need to measure the width, the height and the depth of your laptop.

Some bags like backpack have a vertical section (from North to South) whereas a messenger bag or a sleeve has a horizontal section (from West to East). 

Knowing these extra dimensions will surely help you to decide on your purchase.

Measuring the Diagonal

To measure the actual diagonal length of your laptop, place your measuring tape at the corner of your laptop and stretch the tape across to the bottom end of the corner.

I show you in the illustration below:

Measuring the diagonal laptop

As you can see from the picture above, I measure it from the top corner of the bezel to the bottom edge of the bezel (diagonally).

In this case, the length is 15.5 inches (39.37 cm) long.

When you measure, please ignore the screen size of the laptop because we want to get to the actual size of the dimension. 

My HP laptop screen is 14 inches long, but the overall size is larger due to trim around it.

Now, you’ve got the diagonal length of your laptop. Write it down.

Measuring the Width (Length)

We have covered the measurement of the diagonal dimension. Now let’s move on to the next step; measure the width. 

To measure the width, place your measuring tape at the bottom left corner of the laptop and drag it to the bottom right of the laptop.

Measuring the width laptop

From the picture above, the width of my laptop measures about  13.05 inches (33.15 cm) long. Once you get your width, write it down.

Measuring the Height

To get an accurate measurement of height, you need to close your laptop fully. 

Take your measuring tape and from the side of the laptop, measure the height by placing the ruler at the bottom and the top of the laptop.

Measuring the height laptop

The height of my laptop measures about 2 inches (5.08 cm) high.

The height of the laptop is not as important as other dimensions mentioned earlier because rarely the laptop manufacturer makes the laptop thicker than 2 inches high.

They want to make the laptop as light as possible.

Measuring the Depth

Now to measure the depth of your laptop, place your measuring tape at the top right side of your laptop and drag it to the bottom side of the laptop.

Measuring the depth laptop

The depth of my laptop measures about 9.1 inches (23.11 cm). This is the depth of your laptop and writes it down.

How to Use the Measure App in iOS 12 (or latest update)

If you have an iPhone, you probably don’t need a ruler to measure a laptop. With the iOS 12 update, there’s a new app that comes built-in on iOS devices called Measure.

If you haven’t updated your iPhone for quite some time, please update it first in order to use this app.

Note: If you’re using an Android cell phone, you can download the measure app from Google Play on your phone. 

Please watch this video to learn how to use the Measure app to measure length and dimensions, as well as the level feature.

Here is the step by step of how to measure with the app:

  • Step 1: Launch the Measure app on your iPhone.
  • Step 2: Move your iPhone around until you see this circle appear on your screen. You will see some instructions appear on your screen telling you to move your iPhone around so the app can do a quick scan of what’s around you. 
  • Step 3: Then, move your device around to get the starting point for what you want to measure in the middle of your screen. 
  • Step 4: Tap the plus sign button at the bottom to add a point. If you make a mistake, tap the Undo button in the top left corner to try again. 
  • Step 5: Next, move your iPhone over so that the endpoint of the line you’re measuring appears in the middle of your screen, and tap the plus icon again to end the line. You’ll then see a measurement appear along the line you created. You can create multiple line measurements at the same time if you’re trying to measure dimensions of something. 
  • Step 6: Tap a measurement to see conversions to other units of measurement. Tap Clear in the top right corner to clear all your measurements and start over.

Bear in mind that measuring with the Measure app may not be always correct. Therefore, measuring with a measuring tape probably still the best to get accuracy.

Tips on How to Buy a Laptop Bag Online

If you plan to purchase a laptop back from online stores, you can use the measurement that you got from your laptop. 

For example, if you’re looking for a laptop backpack, you need to look at the length and the width of the bag because the laptop sits vertically from North to South.

Now from our lesson earlier, you should use the measurement of the width and the depth of your laptop.

The width measurement that you have is the same as the length of the backpack. The same goes for the depth measurement, which is equivalent to the width of the laptop backpack.

Likewise, if you’re planning to buy a laptop messenger bag or a tote, it is straight forward because the dimension of these type of laptop bags are horizontally (West to East). 

So take the width measurement as the horizontal dimension and the depth measurement as the height dimension of the laptop messenger bag.

Choosing the wrong size of a laptop bag can harm your laptop because your laptop may not able to fit properly inside the bag.

If you have 14 inches size of a laptop but keep it in a larger backpack, the laptop section compartment may not able to hold and protect your laptop due to too much space.

Laptop Bag Size Guideline

Here are some of the most common questions people always about what size of bags will fit their laptops:

What size laptop bag do I need for a 15.6-inch laptop? 

What size laptop sleeve for a 15.6-inch laptop? 

Can a 15.6 inch laptop fit in a 15-inch case? 

Will a 17-inch laptop fit in a 15-inch bag?

What size backpack do I need for my laptop?

What is the width of the laptop?

It’s hard to tell you the exact answer because it depends on the sizes, dimensions, and design of the bags.

Different manufactures have their own measurement guidelines.

Every bag has the details on what size of a laptop can fit in. 

So, I have created the laptop size guideline table for your reference below. 

Please do remember to take the diagonal measurement of your laptop and compare it to the details on the listing.

You need to add extra inches (or centimeters) to that measurement to fit the outside material surrounding the laptop.

Convert the measurement values from inches to centimeters if necessary because some online retailers will include the cm units in their listing.

Please refer the table below for the right size:

Diagonal laptop (inch) Diagonal laptop (cm) Size Laptop Bag to Choose (inch) Example of Laptops Can Be Fit In
11″ 27.94 cm 11″ MacBook Air 11
12″ 30.48 cm 12″ MacBook 12 inch
12.5″ 31.75 cm 12″ Xiaomi Air 12.5 inch laptop
13.3″ 33.78 cm 13″ MacBook 13 inch
14.1″ 35.81 cm 14″ Any Windows 14.1-inch laptop
14.6″ 37.08 cm 14″ Any Brand 14.6-inch laptop
15″ 38.10 cm 15″ MacBook Pro 15.4 inch laptop
15.6″ 39.62 cm 15″ Any Brand 15 – 15.6-inch laptop
17.3″ 43.94 cm 17″ Any 17.3-inch laptop

Disclaimer: The table above is just a general guideline.


Now you have learned everything you need to know on how to measure the laptop size for the bag. It is a straightforward process. 

If you follow those steps mentioned above, you will find selecting the right laptop bag is not a difficult task.

Make sure you have two different units of measurement; inches, and centimeters because some sellers will use different units of dimension in their listing. 

I hope this guide will help you choose the right bag for your laptop.

If you find this article is helpful, please kindly share it. I very much appreciate it!

Happy Measuring!