How to Measure Your Laptop for a Sleeve or Case
The number in a laptop's name is a screen measurement, taken diagonally, and it says very little about how much room the machine actually needs. Two laptops both sold as fourteen-inch can differ by a centimetre in width and several millimetres in thickness. That gap is the difference between a sleeve that protects your laptop and one that either swallows it or refuses to close.
Measuring takes about a minute. Here is what to measure, and what to do with the numbers once you have them.
The three numbers you need
Close the laptop, set it flat on a desk, and measure it with a ruler or tape in millimetres. Centimetres are fine, but millimetres save you from rounding errors that matter at this scale.
- Width. The longer edge, left to right, at its widest point.
- Depth. Front edge to the back of the hinge, at its deepest point.
- Thickness. The closed height at its thickest point, which on most laptops is at the rear near the hinge. Include the rubber feet.
Three details are worth getting right. Measure at the widest points, including any rubber bumpers or protruding hinge covers, not the flat part of the lid. If the chassis tapers from back to front, use the thicker end. And if you use a hard shell, a skin or a screen protector that adds bulk, measure with it fitted, because that is how the laptop will travel.
How to read a sleeve's dimensions
Sleeve makers usually publish two things, and they answer different questions.
The rated laptop size ("padded compartment for laptops up to 14 inches") is the primary filter. It tells you what the internal compartment is built around, allowing for the padding on either side.
The outer dimensions tell you how large the sleeve itself is: whether it slides into your bag, how it sits under your arm, and what it adds to your carry. They also set a hard ceiling. A laptop can never be wider than the sleeve's outer panel, because padding, lining and seams each take their share. Expect the internal compartment to be roughly a centimetre or two smaller than the outside in width and height.
So the honest check is: does the rated size match your machine, and are your measured width and depth comfortably inside the sleeve's outer dimensions rather than brushing against them?
The measurement most people skip
Thickness is the one that catches people out, because a sleeve's depth is shared. Every NEGOTIA sleeve and folio is 4 cm deep, and that space holds the laptop plus whatever else you put in the other compartments.
A slim modern ultrabook closes at somewhere between 15 and 18 mm. A workstation or gaming laptop can be 25 mm or more. If yours is on the thicker end and you also want to carry a charger, a notebook and a mouse in the same sleeve, the depth is the constraint to think about, not the width. Either accept that the sleeve carries the laptop and little else, or move up to a folio or a bag with a dedicated compartment.
Why the label on the box misleads
A few real examples show how loosely screen size maps to footprint. All three of these are current business laptops, measured by their manufacturers:
| Laptop | Screen | Width × depth |
|---|---|---|
| Lenovo ThinkPad X1 Carbon Gen 12 | 14" | 31.3 × 21.5 cm |
| Dell XPS 14 (9440) | 14.5" | 32.0 × 21.6 cm |
| HP EliteBook 860 G11 | 16" | 35.9 × 25.1 cm |
The first two are both sold as fourteen-inch machines and differ by roughly 7 mm in width. Both sit comfortably inside a sleeve rated to 14 inches. The EliteBook is a different proposition: at 35.9 cm wide it is wider than the entire outer panel of a 35 cm sleeve, so no amount of optimism gets it in. It needs the larger size.
This is also why a laptop that sounds bigger is not always bigger. A 16-inch machine with slim bezels can have a smaller footprint than an older, chunkier 15.6-inch one.
Matching your numbers to a sleeve
NEGOTIA sleeves and folios come in two footprints. Compare your measured width and depth against these.
| Product | Rated for | Outer size (W × H × D) | Weight | Price |
|---|---|---|---|---|
| Mantle Sleeve 14 inch | Up to 14" | 35 × 25 × 4 cm | 425 g | €69 |
| Notion Folio 14 inch | Up to 14" | 35 × 25 × 4 cm | 425 g | €79 |
| Mantle Sleeve 15.6 inch | Up to 15.6" | 40 × 28 × 4 cm | 485 g | €74 |
| Notion Folio 15.6 inch | Up to 16" | 40 × 28 × 4 cm | 475 g | €84 |
| Plenum Folio | Up to 16" | 40 × 28 × 4 cm | 485 g | €84 |
The difference between a sleeve and a folio is what travels alongside the laptop. The Mantle Sleeve keeps it simple: the padded compartment, room for a notebook or chargers, a compartment for a Magic Keyboard and a pocket for a phone or mouse. The Notion Folio adds structured organisation, with a document pocket, a phone pocket, pen holders, a card slot and an AirTag compartment, so it works as a slim carry on its own.
If you own a MacBook you can skip the ruler. The dimensions are published for every model, and our MacBook sleeve size guide maps each current Air and Pro to the sleeve that fits.
When you are between two sizes
Size down to the smaller sleeve your laptop genuinely fits, rather than up. A snug fit is what stops the machine sliding and knocking against the seams, and a sleeve with room to spare is doing less work than it looks.
One last check if the sleeve is going inside a bag: the sleeve's outer dimensions now have to fit the bag's laptop compartment too. Our bags take laptops up to 16 inches in their own padded compartments, which means a sleeve inside one is usually redundant rather than extra insurance. If you are choosing the bag as well as the sleeve, the leather laptop bag buying guide covers what to look for.
Measure once, in millimetres, with the lid closed. Everything after that is straightforward.
