How to Measure Laptop for Bag? | Three Dimensions, One Rule

Screen size (the diagonal number manufacturers advertise) is useless for bag shopping. A 15.6-inch screen laptop can be 14 inches wide, while a 15-inch model might be 15 inches wide, depending on the bezel and chassis design. The only reliable method is to measure the closed body yourself and match those numbers against the bag’s internal compartment dimensions.

How to Measure Width, Depth, and Height Correctly

Close the laptop completely before taking any measurement. An open laptop gives wrong depth and height values every time.

• Width (left to right): Run the tape measure from the leftmost edge to the rightmost edge at the widest point of the closed body. Include protruding rubber feet and ports. A 15.6-inch laptop is typically 14 to 15 inches wide.
• Depth (front to back): Measure from the front edge of the base to the back edge where the screen hinge sits. Include the hinge if it adds bulk. A 15.6-inch model is usually 9 to 10 inches deep.
• Height (thickness): Measure vertically from the bottom surface to the highest point on the closed lid — often the back edge or hinge. Sloped designs still need the absolute maximum height.

Briggs & Riley recommends always measuring the closed device and writing down all three numbers before looking at bags. The bezel alone can add nearly an inch to the width compared to the advertised screen size.

What Size Bag Compartment Do You Need?

The rule is simple: add 0.5 to 1 inch (1.3 to 2.5 cm) to the laptop’s width and depth, and keep the height close to exact. That extra space prevents side pressure and makes insertion and removal easy without letting the laptop shift inside the bag. Height should be snug — too much vertical room lets the laptop slide and take damage during movement.

Check the bag’s internal dimensions, not the “fits up to 15.6-inch” label. Padding, foam liners, and built-in sleeves reduce usable space by up to half an inch per side. Everki’s sizing guides note that a bag marked for a 15.6-inch laptop may not fit a 15.6-inch model from a different brand if the bag’s internal measurements are tight.

Orientation and Hard Cases Matter

Backpack compartments are usually vertical (North-South), while briefcases and totes hold laptops horizontally (East-West). If the bag’s orientation doesn’t match your laptop’s long side, it won’t fit regardless of the numbers.

If you use a hard shell case, measure the laptop with the case on — a protective shell can add significant thickness and width. The same rule applies: measure closed and add the half-inch buffer.

Once you have your three numbers and the buffer rule, you can compare against real bag specs. For a curated selection of bags that meet these sizing rules, see our guide to the best computer bag for travel.

Common Mistakes That Lead to a Bad Fit

• Measuring the screen instead of the body: The bezel adds width and depth. Always measure the closed machine.
• Skipping the buffer: A bag that exactly matches the laptop dimensions crushes the device over time. Always add 0.5 to 1 inch to width and depth.
• Ignoring the hinge: Sloped or raised hinges increase the true height. Measure the highest point, not the average.
• Trusting vague labels: “Fits 15.6-inch” means almost nothing. Only the bag’s internal dimensions in inches or centimeters are reliable.

FAQs

Can I use the screen size to pick a bag?

Screen size alone is not reliable because bezels vary widely between brands. A 15.6-inch laptop from one manufacturer can be up to an inch wider than a 15.6-inch model from another. Always use the body dimensions.

How do I measure if my laptop has a protective case?

Measure the laptop with the protective case on, closed, using the same three dimensions. A hard shell case adds measurable width and thickness that will change the bag size you need.

What if my laptop has a sloped or wedge design?

Measure the thickest point — usually the back edge near the hinge or the port cluster. Sloped designs still need height clearance at the highest spot, not the average.