To measure a laptop for a case, close it and measure the closed device’s width, depth, and thickness, plus the screen diagonal for the size label.
Buying a case or sleeve based only on the “13-inch” or “15.6-inch” label is a gamble. That number is the screen diagonal, and it often has little to do with the physical dimensions of the closed laptop body. One wrong measurement can leave you with a sleeve that’s too tight to zip or so loose your laptop slides around. Here’s how to get it right in under five minutes.
Why Screen Size Isn’t Enough
A “14-inch” laptop from one brand can be a completely different physical size than a “14-inch” from another. The advertised size measures the screen corner-to-corner, not the body. Manufacturers confirm this: one brand’s official guide says to measure the closed laptop’s height, width, and depth for fit, while another defines sleeve sizing by the diagonal screen measurement alone.
Ignore the size label on the product page; trust the numbers.
The 4 Measurements You Need
Close the laptop fully and place it on a flat, hard surface. You’ll need a tape measure or a ruler. Don’t measure while it’s open, and don’t include the rubber feet if you can help it—though note them separately if they’re tall.
- Screen diagonal (for the size class): Measure from one corner of the screen to the opposite corner. This tells you which labeled size to shop for, but nothing more.
- Width: The longest horizontal edge, left to right, on the closed laptop.
- Depth: The front-to-back edge, from the edge nearest you to the hinge.
- Thickness: From the bottom of the feet to the top of the lid, measured at the thickest point.
Write all four numbers down. When you’re comparing cases, you’ll check your width, depth, and thickness against the case’s stated interior width, height, and depth. If the case’s interior dimensions are larger than your laptop’s, it will fit.
| Measurement | How To Measure It | What It Tells You |
|---|---|---|
| Screen diagonal | Corner to opposite corner of the display | Which “size class” to shop for |
| Width | Longest horizontal edge, left to right | Fits the case’s interior width |
| Depth | Front-to-back edge of the closed body | Fits the case’s interior depth |
| Thickness | Bottom to top at the thickest point | Fits the case’s interior height |
Check the Case’s Interior, Not the Label
Manufacturer guidance is consistent: compare your closed laptop’s dimensions to the case’s internal dimensions. One brand’s sizing guide stresses this exact point, noting the bag should allow extra clearance, including at least half an inch more than your laptop’s depth for easy insertion. Another publishes bag specs using interior width, height, and thickness—that’s the data you want.
Leave a small buffer. A sleeve that’s exactly your laptop’s size will be a struggle to zip, and a too-tight fit can stress the zipper and edges or press against the display when closed. A too-loose fit lets the laptop slide around, which reduces protection. Aim for about a quarter to half an inch of clearance on the depth and width.
Don’t Forget the Protrusions
Your laptop’s body isn’t always a perfect rectangle. Port bumps, attached dongles, thick rubber feet, and hinge bulk all add height or width that your tape measure might miss. If your laptop has any of these, add their size to your base numbers before you compare them to a case.
The most common mistake is measuring the open screen or the keyboard deck instead of the closed body, which gives you numbers that don’t match any case spec. The second most common is ignoring the case’s interior dimensions entirely. If you’re shopping for a specific model like a 16-inch MacBook Pro, it’s worth checking a vetted roundup to see which cases actually fit its dimensions before you measure and buy.
If you’re looking for a case for the 16-inch MacBook Pro, our tested roundup of the best cases for MacBook Pro 16 shows which options fit its exact profile.
FAQs
Does a 13-inch case fit a 14-inch laptop?
Sometimes, but don’t rely on it. The “13-inch” label refers to the screen diagonal, not the body size. A 14-inch laptop with a slim bezel can have a body the same width and depth as a bulkier 13-inch model. Always compare the closed laptop’s width, depth, and thickness to the case’s interior dimensions, not the screen-size label.
Should I measure the laptop open or closed for a case?
Measure it closed. A case or sleeve is designed to hold the laptop in its closed state, so the relevant dimensions are the closed body’s width, depth, and thickness. Measuring it open gives you the screen size and keyboard deck size, which don’t match any case spec and will lead to the wrong purchase.
How much clearance should a laptop sleeve have?
For width and thickness, a quarter to half an inch of extra room is a safe target. Too much clearance lets the laptop slide and reduces protection; too little makes the case hard to zip and can stress the zipper or press on the display.
References & Sources
- wikiHow. “How to Measure Your Laptop Computer.” Provides the standard measurement method for laptop width, depth, and screen size.