Which Gym Backpack Size? 45L vs 25L vs 15L vs 9L
Liters on a tag don't tell you if your shoes, belt and laptop will fit. Here's what each RBST tactical backpack size actually holds, who it's for, and how to choose without overbuying or under-packing.
You buy a backpack, get it home, and the first morning you try to pack shoes, a lifting belt, knee sleeves, a shaker, a change of clothes and your laptop. Something stays on the counter. Or you go the other way, buy the biggest bag on the shelf, and haul a half-empty duffel on your back to a 45-minute class.
Picking a gym backpack size is really about one question: what do you carry on your normal training day? Not your competition weekend. Not your once-a-year trip. Your regular Tuesday.
RBST makes its tactical backpack in four sizes: 9L, 15L, 25L and 45L. Same Honey Badger attitude, very different jobs. In this guide we compare them by capacity, dimensions, features and price using the specs on our product pages, then match each one to a real training routine. If you're shopping specifically for race day, we cover that in Best Backpack for HYROX Race Day, so this post focuses on everyday gym life.
Quick tip before you start: lay out everything you bring on a normal day. That pile is your answer.
The Quick Answer
9L ($55): essentials only, like phone, keys, grips, rope and chalk. 15L ($65): small gym setup without shoes plus full clothes. 25L ($85): the everyday sweet spot, shoes, clothes, accessories and a laptop compartment. 45L ($105): full training setup, gym-to-work days, and competition travel. Not sure? Most athletes who train before or after work land on 25L; anyone carrying a belt, sleeves, shoes and a laptop daily should go 45L.
RBST Backpack Sizes Compared
Specs and prices come from the RBST product pages at the time of writing.
| Feature | 9L | 15L | 25L | 45L |
|---|---|---|---|---|
| Price | $55 | $65 | $85 | $105 |
| Dimensions | Most compact | 13" x 11" x 6" | 16" x 12" x 8" | 20" x 12" x 10" |
| Fabric | Not listed | 900D Oxford | 900D Oxford | 900D Oxford |
| Laptop compartment | Not listed | Not listed | Yes | Yes |
| Fits shoes + clothes | No | Tight | Yes | Yes, with room |
| Colors | 4 | 3 | 8 | 8 |
| Best for | Essentials, errands | Light gym days | Gym + work/school | Full setup, travel, comps |
Color counts reflect live variants at writing. Stock changes, so check the product page.
What Actually Fits in Each Size
9L: The Essentials
Phone, keys, wallet, pull-up grips, a jump rope, chalk ball, thumb tape, wrist wraps and a small towel. Great for drop-in classes when you're already dressed to train.
15L: Light Gym Day
Everything in the 9L plus a shaker, a T-shirt, sweatbands and a pair of knitted knee sleeves. Shoes plus a full change of clothes gets tight.
25L: Everyday Training
Training shoes, shorts and a shirt, grips, rope, wraps, sleeves, a water bottle, plus a laptop in its own compartment. The commuter's choice.
45L: Full Setup
Shoes, a lifting belt, 7mm sleeves, full change of clothes, towel, food, laptop and accessories. Built for long days, double sessions and comp weekends.
How to Pick Your Size in 4 Steps
Lay it out. Put everything you carry on a normal training day on the floor.
Count the bulky items. Shoes, a belt, thick knee sleeves and a laptop take the most space. Two or more usually means 25L or 45L.
Think about your whole day. Gym only? Go smaller. Gym, work and gym again? Go bigger.
Leave a little room. A bag packed to bursting is hard to zip and hard to find things in. Size up if you're right on the edge.
Which Athlete Are You?
The class-and-go athlete. You show up dressed, train, and leave. You need grips, rope and tape. The 9L or 15L keeps it light.
The commuter. You train before or after work and carry a laptop. The 25L is the balance point: laptop compartment, room for shoes and clothes, and still compact at 16 x 12 x 8 inches.
The strength athlete. Belt, 7mm sleeves, lifting shoes, wraps and chalk add up fast. Go 45L. Need a belt? Start with our belt sizing guide.
The competitor. Comp weekends mean multiple outfits, food and every piece of gear you own. The 45L is the one. For HYROX specifically, read our race-day size chooser.
Honest Trade-Offs
Smaller bags are lighter, easier to stash in a cubby, and force you to pack only what you need. The trade-off is no room for shoes plus clothes.
Bigger bags carry everything, but they're bulkier on a short gym trip, and the 45L's 10-inch depth may not fit every airline carry-on limit. None of the line is advertised as fully waterproof, so protect electronics in heavy rain.
What to Pack, by Size
- Every size: grips, thumb tape, sweatbands, wrist wraps.
- 15L and up: jump rope, knitted knee sleeves, shaker.
- 25L and up: training shoes, clothes, laptop.
- 45L: lifting belt, 5mm or 7mm sleeves, towel, food, extra clothes.
More ideas in What to Pack in a Gym Backpack. Wondering which accessory does what? Read Wrist Wraps vs Sweatbands vs Grips.
Keep Your Backpack Fresh
Gym bags get sweaty. Pull wet gear out after every session so it can dry, and spot-clean the bag with mild soap and a damp cloth. Let it air-dry fully before you pack it again. Knee sleeves are the usual source of gym-bag smell, so see How to Wash Knee Sleeves and Stop the Smell.
The RBST Tactical Lineup
9L Tactical · $55
Compact everyday carry. Adjustable straps, soft back panel, padded handles.
25L Tactical · $85
900D Oxford, 16 x 12 x 8 inches, laptop compartment, flag patch included.
45L Tactical · $105
900D Oxford, 20 x 12 x 10 inches, laptop compartment, built for full setups.
Gym Backpack Size FAQs
What size backpack do I need for the gym?
Most athletes who carry shoes, a change of clothes and a few accessories land on 25L. If you also bring a laptop, a belt, knee sleeves and a full change of clothes, look at 45L. If you only carry keys, phone, grips and a rope, 9L or 15L is enough.
Is 25L big enough for a gym bag?
For many people, yes. The RBST 25L measures 16 x 12 x 8 inches and has a laptop compartment. It handles a training day plus work. If you carry shoes, a belt and a full change of clothes every day, 45L gives you more room.
Is 45L too big for everyday use?
It depends on your day. The 45L is 20 x 12 x 10 inches, which is big for a short gym trip but ideal if you go gym to work to gym, or travel for competitions.
What fits in a 9L backpack?
The 9L is for essentials: phone, keys, wallet, grips, a jump rope, chalk, tape and a small towel. It is not built for shoes plus clothes.
What are the RBST backpack dimensions?
Per the product pages: 15L is 13 x 11 x 6 inches, 25L is 16 x 12 x 8 inches and 45L is 20 x 12 x 10 inches. The 9L is the most compact of the line.
Which RBST backpacks have a laptop compartment?
The 25L and 45L product pages list a dedicated laptop compartment. Check your laptop size against the bag before you buy.
Are RBST backpacks carry-on approved?
Airline limits vary. The 45L depth of 10 inches may exceed some carry-on limits; the 25L at 16 x 12 x 8 may work as a personal item on some airlines. Always check your airline first.
What material are the RBST tactical backpacks made from?
The 15L, 25L and 45L product pages list 900D Oxford fabric.
Are RBST backpacks waterproof?
They are not advertised as fully waterproof. Protect electronics in heavy rain.
How much do the RBST tactical backpacks cost?
At the time of writing: 9L $55, 15L $65, 25L $85 and 45L $105. Check the product page for current pricing.
Which size is best for HYROX race day?
We cover that in detail in our HYROX race-day backpack guide. In short, most athletes pick 25L or 45L depending on how much they bring.
Do the backpacks come with a patch?
The 15L, 25L and 45L pages list a flag patch included. The patch extender is sold separately for $9.99.
How do I clean my RBST backpack?
Empty it, shake out debris, spot-clean with mild soap and a damp cloth, avoid harsh chemicals and let it air-dry fully.
Can I own two sizes?
Plenty of athletes do: a 25L or 45L for full training days and a 9L or 15L for quick sessions, errands and travel days.
Pack Light or Pack Everything. Just Show Up.
Four sizes, one mindset.
Shop 25L · $85 Shop 45L · $105 All Tactical BackpacksForged in Grit. Built by Community. Not Just a Brand — A Movement.
