Backpack Size Guide: What are Normal Backpack Dimensions & Liters?

If you’ve ever shopped for a backpack, you know how tricky it can get. One brand lists its bag as “25L,” another says “18 × 12 × 7 inches,” and a third just promises, “fits laptops up to 16 inches.” Helpful? Not really.

So what exactly counts as a normal backpack? Is it the compact Herschel Classic you see on students? The commuter-friendly eBags Professional Slim? Or the slightly bulkier but oh-so-comfy North Face Borealis?

The truth is, there isn’t one single “normal size.” But there is a sweet spot that works for most people, and that’s what we’ll explore in this guide.

By the end, you’ll know exactly what size backpack makes sense for school, work, travel—or just running around town.

TL;DR: The “Normal” Backpack Size is…

If you’re only here for the measurements, here is the answer:

The consensus for a comfortable, everyday backpack is the Medium range, fitting the Goldilocks Zone for school, work, and daily carry:

BUT WAIT: Dimensions matter more than liters. If you’re traveling, your bag must be 22×14×9 inches or less to qualify as a carry-on.

Scroll down to our full size chart and airline rules section for the exact breakdown you need to avoid fees!

Why Backpack Dimensions (and Liters) Matter for Comfort & Travel

It’s tempting to think, “bigger is better.” But trust me—after carrying a 40L hiking pack through airports when all I needed was a laptop and charger, I can tell you that’s not true.

A backpack that’s too big makes you overpack, and you end up with sore shoulders and an aching back. A bag that’s too small? Frustration city—you can’t even fit your water bottle.

Take the North Face Borealis (28L) for example. It’s roomy enough for a laptop, notebooks, and lunch, but doesn’t look bulky on your back. Compare that to the Samsonite Tectonic Lifestyle Crossfire (40L)—great for overnight business trips, but way too much bag for a daily commute.

Bottom line: dimensions matter because they affect comfort, organization, and even travel rules.

How Backpack Size is Measured: Liters vs. Dimensions (H x W x D)

Here’s the part many people overlook: backpack size isn’t just about “liters.”

• Dimensions (inches/cm): Height × Width × Depth tells you how the bag will actually look on your back and whether it fits under an airplane seat. Example: the Herschel Little America is roughly 19.25 × 11.25 × 7 inches.
• Capacity (liters): This measures how much space the bag holds. The Osprey Daylite Plus, for example, is 20L—perfect for hikes and city trips.

But here’s the catch: not all 25L backpacks feel the same. A slim 25L laptop bag like the eBags Professional Slim carries less clothing than a 25L hiking daypack like the Osprey Talon. Shape and design matter just as much as liters.

So when you’re comparing backpacks, always check both the liters and the actual dimensions.

The Average Dimensions of a “Normal” Backpack (The 20L-30L Sweet Spot)

For everyday use, a backpack that’s around 18 × 12 × 7 inches (20–30L) hits the sweet spot.

That usually means:

• Height: 17–19 inches
• Width: 12–13 inches
• Depth: 6–8 inches
• Capacity: 20–30 liters

This range is what you’ll find in popular everyday bags like the North Face Jester (27L), the Herschel Classic XL (30L), or the SwissGear 1900 ScanSmart (31L).

These backpacks are big enough for a 15–16-inch laptop, a lunchbox, a water bottle, and daily essentials—but not so big that they become a burden.

Think of them as the “Goldilocks zone” of backpacks: not too small, not too big—just right.

Backpack Categories & Their Typical Dimensions

Not all backpacks serve the same purpose. Here’s how the dimensions break down across categories:

• School Backpacks: Usually around 17 × 12 × 6 inches (20–25L). Bags like the JanSport SuperBreak One or Herschel Pop Quiz are classics for students.
• Laptop & Work Backpacks: About 18 × 12 × 7 inches (22–30L). The eBags Professional Slim Laptop Backpack is a prime example—sleek, organized, and commuter-friendly.
• Travel Daypacks: Around 19 × 13 × 8 inches (25–35L). The Osprey Daylite Travel Pack is a go-to for weekend trips or city exploring.
• Carry-On Backpacks: Sized closer to 20–22 × 14 × 9 inches (35–45L). The Nomatic Navigator Backpack (32L, expandable to 41L) is designed for air travel.
• Small Everyday Bags: 15–16 × 10 × 5 inches (15–20L). Think Fjällräven Kånken—minimalist and stylish for light carry.

Each category has its own normal, depending on what you’ll use it for.

Backpack Size Chart: Liters and Dimensions Cheat Sheet

Here’s a quick cheat sheet:

• Small (15–20L): Typical Dimensions (15–16 × 10–11 × 5–6 in) daily Light carry, errands, gym. Example: Fjällräven Kånken (16L).
• Medium (20–30L): Typical Dimensions (17–19 × 12–13 × 6–8 in) The “normal” backpack size. Example: North Face Borealis (28L).
• Large (30–45L): Typical Dimensions ( 19–22 × 13–14 × 8–9 in) Travel and overnight bags. Example: Nomatic Navigator (41L expanded).

Most people find themselves happiest in the medium range.

How to Choose the Right Backpack Size for Your Needs

Here’s the human way to think about it:

1. List what you carry daily. Laptop, lunch, charger? A 20–25L like the Herschel Pop Quiz will do. Gym shoes and a jacket, too? Step up to a 28–30L like the North Face Borealis.
2. Check laptop compatibility. A “15-inch backpack” doesn’t always fit a 15.6-inch gaming laptop. The SwissGear 1900 (31L) is better for bulkier machines.
3. Prioritize comfort. Look for padded straps, breathable back panels, and (if you carry heavy loads) chest or waist straps. Osprey bags are excellent for ergonomics.
4. Think flexibility. Expandable backpacks like the Nomatic Navigator adapt to both daily carry and travel.

It’s not just about liters—it’s about how the bag fits your actual life.

Backpack Sizes for Air Travel: Carry-On & Personal Item Rules

Travel adds another layer: airline rules.

• Most U.S. airlines allow carry-ons up to 22 × 14 × 9 inches (about 40–45L).
• Personal item backpacks must fit under the seat—usually around 18 × 14 × 8 inches (20–25L).

That’s why backpacks like the Tortuga Outbreaker 35L and Nomatic Navigator 32L/41L are so popular with frequent flyers. They max out airline limits while staying comfortable to wear.

Pro tip: airlines measure dimensions, not liters—so always compare your bag’s inches against airline rules.

Common Mistakes When Choosing Backpack Dimensions (And How to Fix Them)

Here are the traps I see people fall into all the time:

• Buying a huge 45L bag “just in case” and ending up with sore shoulders.
• Ignoring depth—a slim 20L can look neat, while a chunky 20L sticks out awkwardly.
• Not checking laptop sleeves—your 17-inch Dell won’t fit in a 30L slim Herschel.
• Forgetting about torso length—a 19-inch tall bag can overwhelm shorter users.

The solution? Try the backpack on if you can—or at least compare its measurements to one you already own.

FAQs: Your Top Questions on Backpack Dimensions and Size

Final Thoughts: Finding Your Perfect Backpack Size

So, what are the dimensions of a normal backpack?

Most people are happiest with something around 18 × 12 × 7 inches (20–30 liters)—big enough for everyday essentials, small enough to stay comfortable.

That’s why backpacks like the North Face Borealis, Herschel Pop Quiz, and eBags Professional Slim are so popular—they nail that middle ground.

But “normal” is ultimately what fits your life. Maybe you’re a minimalist with a 16L Fjällräven Kånken, or maybe you’re a frequent flyer with a 40L Nomatic Navigator.

The key is to match the backpack to your lifestyle—not the other way around.