Michael Turner
Typical capacities across the maker’s lineup: small youth models ~8–12 L; compact daypacks ~20–28 L (SuperBreak ≈25 L); student/dual-compartment styles ~30–35 L (Big Student / Right Pack ≈32–34 L); larger travel or weekend variants ~40–50 L.
Use recommendations: for commuting with a 13–15″ laptop and lunch choose 25–30 L; for a full school load of textbooks and folder(s) choose 30–35 L; for a 1–2 night trip choose 40–50 L; for preschool/elementary children choose under 12 L.
To verify capacity from dimensions, use this quick calculation: L = (height_cm × width_cm × depth_cm) ÷ 1000. Example: 45 × 30 × 18 cm → 24.3 L. For imperial units convert inches to cm first (1 in = 2.54 cm) or use approximate conversion 1 L = 61 in³.
Packing tips: prioritize a model with a padded sleeve if you carry a laptop; choose one with a sternum or waist strap for loads above 10–12 kg; allow a 10–20% margin if you alternate between light and heavier daily loads.
Capacity guide for common daypacks
Choose a 25 L pack for everyday carry; opt for 30–35 L when you need to haul textbooks, a 15″ laptop and lunch; select 40–45 L for overnight trips with a change of clothes and basic toiletries.
- Classic school-style pack – ~25 L: fits A4 folder, 13–15″ laptop sleeve, small pencil case and a medium water bottle.
- Padded laptop commuter – 28–32 L: dedicated laptop compartment, extra organizer pockets, room for charger and a light jacket.
- Two-compartment student model – 33–35 L: holds 2–4 heavy textbooks, spiral notebooks, lunchbox and a 15″ laptop.
- Weekend/gear pack – 40–45 L: packing cube for clothing (2–3 shirts, trousers, socks), toiletry kit, compact rain jacket and snacks.
- Travel carry-on style – 45–60 L: fits 3–5 days’ clothing, packing cube, shoes and a small day pouch; check airline carry-on limits before flying.
Packing benchmarks (approximate): 1 small laptop + charger = 3–5 L; single large textbook = 2–3 L; insulated lunchbox = 3–5 L; water bottle = 1–2 L of occupied volume. Use these to estimate required capacity rather than relying on model names alone.
- For daily academic use: 25–33 L keeps weight manageable and fits standard school gear.
- For mixed use (work + gym): 30–40 L allows separate shoe or gym kit without cramming the laptop compartment.
- For short travel: 40–50 L provides space for clothing plus a compact toiletry kit and day-sack.
Comfort rules: keep loaded weight under 10–12 kg for all-day wear; adjust sternum strap and use padded hip belt on packs above 35 L to shift load off the shoulders. Choose a model with a ventilated back panel if you carry it for long periods.
For comparative shopping, check model specs listed by volume and internal dimensions, and verify external pocket layout for your specific items. Related gear reviews: best cylinder lawn mower australia.
Exact capacities for SuperBreak, Right Pack and Big Student
SuperBreak – 25 L; Right Pack – 31 L; Big Student – 34 L.
SuperBreak (25 L): Compact daypack suited for light loads – fits an A4 folder, a slim 13″ laptop or tablet, a small water bottle and a few notebooks. Single main compartment plus front stash pocket; recommended when total carry volume should stay under ~25 L.
Right Pack (31 L): Mid‑size school/commuter pack designed for textbooks and gadget gear – accommodates a 15″ laptop in a sleeve or sleeve insert, multiple textbooks, lunch and a water bottle. Leather‑bottom versions add abrasion resistance; choose this model when you need ~31 L of usable space without moving up to the largest option.
Big Student (34 L): Largest of the three for heavy loads or multi‑item school days – two large compartments, a dedicated padded laptop sleeve (fits most 15″ devices), space for binders, bulky textbooks and a full‑size water bottle. Pick this model when total carried volume will approach or exceed 30 L and you want extra organizational capacity.
Measure pack volume at home using dimensions or a fill method
Quick recommendation: measure internal length × width × depth for every compartment, convert cubic centimetres to L by dividing by 1,000, then add compartment volumes; round to the nearest 0.5 L.
Dimension method – practical tips: use a flexible tape measure; take width at the widest internal point, height from base to top seam, depth from front to back at the deepest point. For a rectangular approximation use: volume (cm³) = length × width × depth. For curved pockets approximate with a cylinder: volume = π × radius² × height (use radius = half of diameter). Record each pocket separately (main, front sleeve, laptop sleeve, hipbelt pockets) and sum the results.
Example: main compartment 45 cm × 30 cm × 18 cm = 24,300 cm³ → 24.3 L; laptop sleeve 40 cm × 27 cm × 2 cm = 2,160 cm³ → 2.16 L; bottle pocket approximated as cylinder with diameter 7 cm and depth 18 cm: π×(3.5²)×18 ≈ 693 cm³ → 0.69 L. Total ≈ 27.15 L → report as ~27 L.
Fill method – step-by-step: place a large, food-grade resealable bag inside a compartment, open the mouth wide so the bag reaches all corners, fill with uncooked rice or small dry beans (they conform and don’t leak). Push out trapped air, seal, remove and pour contents into a measuring jug graduated in mL (or weigh on a kitchen scale and treat 1 g ≈ 1 mL). Convert mL to L by dividing by 1,000.
Practical example: bag from main compartment yields 4,800 mL → 4.8 L. Repeat for each pocket and sum. Use multiple bags for large compartments if one bag won’t reach corners; combine measurements.
Adjustment and final reporting: subtract ~5–10% for thick internal padding or stiff frames that reduce usable volume. Include external attachment points separately (roll-top extension, lash straps). Report a conservative rounded figure (nearest 0.5 L) and state whether that value includes external pockets or only internal usable space.
Converting labelled capacity to usable packing space by accounting for compartments and shape
Reduce the labelled value by 10–30% as a baseline then refine with the coefficients and fixed-volume deductions below to estimate actual usable packing volume (expressed in L).
Quick coefficient guide: boxy single-compartment designs: 0.95–1.00; curved or tapered shells: 0.85–0.95; multiple internal organisers or dedicated pockets: 0.75–0.85; rigid framesheets or thick padded back panels: subtract 1–3 L.
Fixed-volume items to subtract: laptop sleeve – typical volumes: 13″ ≈ 2.0 L, 15″ ≈ 3.5 L, 17″ ≈ 4.5 L; hydration bladder pocket – 1–3 L depending on rated bladder; internal tool/organiser panels – 0.5–1.5 L.
Practical formula: usable_L = labelled_L × shape_factor × compartment_factor − reserved_L. Example values: shape_factor = 0.90 for rounded shells, compartment_factor = 0.80 for bags with multiple organisers.
Worked examples: 25 L boxy daypack without laptop → usable ≈ 25 × 0.95 × 0.95 = 22.6 L (round to 22–23 L). 30 L commuter with 15″ laptop and curved front → usable ≈ 30 × 0.90 × 0.80 − 3.5 = 18.1 L (round to 18 L).
Design-specific adjustments: roll-tops with uncompromised interior tend toward the high end of coefficients; framed hiking packs often lose 5–10% to internal structure; side bottle pockets add external carrying but do not increase main compartment volume.
Packing tips to reclaim usable space: use compression straps to reduce dead air and recover 5–10% usable volume; remove non-structural internal dividers when possible; place flat items (tablet, clothes) against padded panels to minimise wasted curvature zones.
Choose by use: 20–25 L for school, 25–30 L for commuting, 15–20 L for day hikes, 30–40 L for short trips
20–25 L campus pack: fits one 13–15″ laptop, 2–3 spiral notebooks, pencil case, lunch box, and a 500–750 ml water bottle. Target a model with a padded laptop sleeve, internal organiser pockets, and a reinforced base. Typical loaded weight: 3–5 kg.
- Packing checklist: 1 laptop (1–2 kg), 2 notebooks (0.5–1 kg), lunch (0.5 kg), water (0.5–0.75 kg), chargers/keys (0.2–0.5 kg).
- Choose a panel loader for easy access to papers; choose a lightweight top-loader if you prioritize minimalism.
25–30 L commuter pack: accommodates 15″ laptop, lunch, light jacket, small gym kit, plus accessories. Opt for weather-resistant fabric, a padded laptop compartment, and a sternum strap for stability on bikes or scooters. Typical loaded weight: 4–6 kg.
- Packing checklist: 1 laptop (1.5–2.5 kg), charger & mouse (0.3–0.6 kg), change of shirt (0.2–0.5 kg), compact umbrella, lunch, water.
- Look for a trolley sleeve if you alternate between subway and short flights.
15–20 L daypack for hikes: carries 1–2 L of water, a lightweight wind/rain shell, snacks, first-aid, map/phone, and a small camera. Pick a pack with a ventilated back panel, hip-belt or stabilising straps for loads above ~2.5 kg, and external pockets for quick access gear. Typical loaded weight: 1.5–3.5 kg.
- Packing checklist: water (1–2 L), layers (0.3–0.6 kg), snacks (0.2–0.5 kg), headlamp/first-aid (0.1–0.3 kg), sunscreen.
- For hikes longer than 8–10 km or technical terrain, step up to 20–25 L with a proper hip-belt.
30–40 L short-travel bag: fits 2–4 days of clothing with packing cubes, one pair of shoes, toiletries, and a small electronics kit. Prefer panel loaders or travel-oriented designs with compression straps and lockable zips; aim for carry-on compatible dimensions (~40 L depending on shape). Typical packed weight: 6–10 kg.
- Packing checklist for a 2–3 night trip: 2 shirts, 1 pair trousers, underwear/socks, lightweight jacket, toiletries in a 1 L pouch, chargers, small shoe (store outside main cube).
- Use compression packing cubes to reduce bulk; choose a squarer profile to match cabin limits linked here: best luggage for 3 day business trip.
Quick selection rules
- Match capacity to daily load: plan items, weigh if unsure, then add ~10–15% spare volume for unexpected items.
- Prefer models with dedicated laptop sleeves for work/school; choose ventilated backs and hip-belts for hiking use.
- For mixed use (commute + short travel), pick 30–35 L with compressible packing cubes so the bag works as both a day pack and a 48‑hour travel bag.
Extras: if you pack beach gear or need a compact shade option for a day trip, consider pairing a 30–40 L travel pack with a lightweight umbrella set: best outdoor beach umbrella and chairs victoria.
Pack counts per L: shirts, textbooks and gadgets – practical examples
Choose a 25–30 L pack for everyday school use: fits 2 T‑shirts, 3 medium textbooks, a 13″ laptop and chargers/headphones with room for a light jacket or lunch.
Per-item volume estimates (approximate usable volume in L)
T‑shirt (folded): 0.8–1.5 L; polo/thin sweater: 1.5–2.5 L; pair of jeans: 2–3 L. Paperback (300–400 pages): 0.6–0.9 L; medium hardcover/textbook: 1.5–2.0 L; oversized textbook: 2.5–3.5 L. 13″ laptop in sleeve: 1.2–1.8 L; 15″ laptop in sleeve: 2.0–2.8 L. Over‑ear headphones: 0.6–1.2 L; phone + charger + cables: 0.1–0.4 L; 10,000 mAh power bank: ~0.12 L; slim tablet/e‑reader: 0.8–1.5 L.
Packing examples by capacity (practical usable load per listed L)
12 L – commuter/daypack: 1 T‑shirt (1 L), 1 paperback (0.8 L), phone+charger (0.2 L), compact water bottle (1 L), small lunch (1.5 L) = ~5.5 L used; remaining space for small extras or a light rain jacket packed flat.
18 L – compact school set: 1 T‑shirt (1 L), 1 pair jeans or 1 sweater (2–2.5 L), 2 paperbacks or 1 medium textbook (1.6–2 L), 13″ laptop (1.5 L), cables/headphones (0.4 L) = ~6.5–7.5 L used; leaves room for snacks and a pencil case when arranged vertically.
25 L – standard school/day option: 2 T‑shirts (2–3 L), 3 medium textbooks (4.5–6 L), 13″ laptop in sleeve (1.5 L), chargers/headphones/power bank (0.6 L), water bottle (1–1.5 L) = ~10–12.5 L used; remaining volume accommodates a light jacket and a small folder.
30 L – full school load or short overnight: 3 T‑shirts (3–4.5 L), 4 medium textbooks (6–8 L), 13–15″ laptop (1.5–2.5 L), headphones + chargers (0.6 L), lunchbox (1.5–2 L) = ~12.6–17.6 L used; extra interior pockets handle toiletries or a camera.
35–40 L – short trip / heavy course load: 4 shirts + 1 sweater (5–7 L), 5–6 textbooks or a mix of textbooks + binders (8–12 L), 15″ laptop (2–2.8 L), larger headphones (1 L), toiletry kit and packing cube (2–3 L) = ~18–25 L used; structure allows separation of clothes and study materials.
Packing notes: load the laptop in a padded sleeve first, position heavy textbooks low and close to the back panel, compress clothing into a small cube to free structured corners, keep chargers and small gadgets in a single pocket for quick access, and reserve front pocket for frequently used items. For mixed loads, subtract ~10–15% from nominal capacity to allow for awkward shapes and compartments when estimating counts.
Comparing labelled volume across brands – reasons for variance and comparison tips
Pick a model with a labelled capacity 10–20% larger than the internal packing space you need; this margin compensates for padding, internal organisers and shape loss.
Different manufacturers measure capacity using different approaches. Typical causes of mismatch between label and real usable space:
– external dimension measurement (width × height × depth) often overstates usable room by roughly 5–15% because shell thickness, seam allowances and curved panels are included;
– counting only the main compartment can understate total usable space when exterior pockets and hipbelt pouches are substantial (these can add 0.5–3 L depending on design);
– fill-methods (stirred beads or foam) measure practical packable volume most closely, but brands rarely publish that data and may exclude small accessory pockets;
– internal dividers, laptop sleeves and sewn organizers reduce continuous packing volume; a padded laptop compartment typically removes 1–3 L of contiguous space on daypacks;
– rounded marketing figures: manufacturers round to the nearest whole L and sometimes sum compartment claims, producing apparent inconsistencies between labels and real use.
Practical comparison checklist
Before deciding between two labelled capacities, check and compare these items on spec sheets and product photos:
– Measurement note: look for “measured via fill” vs “external dimensions” or “main compartment only.”
– Pocket inventory: list and roughly size exterior pockets, hipbelt pockets and internal sleeves; add their volumes if the brand lists them.
– Opening and shape: a wide U-shaped lid or full clamshell front yields more usable packing area than a tapered cone of the same labelled volume.
– Internal padding thickness: subtract ~0.3–0.8 L per padded wall for daypack-class bags; subtract 1–2 L total for heavily padded laptop sleeves.
– Compression/expansion features: compression straps can reduce usable bulk; expansion panels or removable pouches increase it.
– Real-world photos: compare product shots with items you know (books, water bottles) to gauge true usable size.
Typical measurement methods and expected bias
| Method | What is counted | Typical bias versus usable packing volume |
|---|---|---|
| External dimensions (W×H×D) | Shell outside measurements including curved panels | Overstates by ~+5% to +15% |
| Main compartment only | Internal main pocket; excludes exterior and small pockets | Understates total by −5% to −20% depending on pocketing |
| Fill test (beads/foam) | Actual packable voids measured directly | Closest to usable: −2% to +5% |
| CAD/modelled volume | 3D model internal cavities; may assume ideal packing | Varies ±0–10% depending on padding/seam allowances |
| Marketing summed compartments | Manufacturer sums individually rounded pocket volumes | Can appear inflated by +5% to +20% |
Final selection rule: when labels are equal, choose the design with fewer internal stitched dividers, a wider opening, and clear manufacturer notes showing fill-method measurement or explicit inclusion/exclusion of pockets; expect real-world usable volume to differ from the label by about ±10% depending on those factors.
FAQ:
How many litres is a typical JanSport backpack?
Most JanSport backpacks used for school or daily carry sit in the 20–35 litre range. Smaller daypacks are about 20–25 L, while larger student or travel styles are commonly 30–35 L. For the precise number check the model specifications.
How do I convert a JanSport volume listed in cubic inches to litres, and how can I measure the pack myself?
To convert cubic inches to litres, divide the cubic-inch value by 61.024 (1 litre ≈ 61.024 cu in). Example: 1,500 cu in ÷ 61.024 ≈ 24.6 L. If no volume is provided, measure the main compartment in centimetres (height × width × depth), multiply to get cubic centimetres, then divide by 1,000 to obtain litres (e.g., 45 cm × 30 cm × 18 cm = 24,300 cm³ = 24.3 L). Keep in mind reported volume can differ from usable space because of curved shapes, external pockets and internal dividers. As a rule of thumb: 20–25 L covers a laptop, a few notebooks and a bottle for daily use; 30–35 L fits a heavier school load or light overnight gear. Use the exact model name on JanSport’s website or product tag when you need an official figure.
