DOC KB-SIZ-004REV 2026-09-21CLASS: PUBLIC
How to Choose the Right Protective Case Size
Direct answer
Start from the largest item's internal footprint plus foam clearance (2–5 mm per side), add the depth of every layer of foam above and below, then check three external constraints: airline check-in limits if it flies, vehicle or rack stowage if it drives, and total loaded weight — wheels and telescoping handles add roughly 40–60 mm of height and 1.5–2.5 kg.
§01Worked method
- Measure the payload at its widest points, including connectors, knobs, straps and cable bends.
- Add cavity clearance: 2–5 mm around each item silhouette inside the foam cavity.
- Add foam stack: lid foam + cavity layer + base foam (commonly 50–110 mm total for equipment loads).
- Reserve accessory volume: chargers, manuals and spare parts typically need 15–25 % more cavity area than the main unit alone.
- Check external envelope: shell walls add 25–60 mm per axis depending on material; add handle/wheel height for rolling cases.
§02Airline and freight checkpoints
| Constraint | Limit | Applies to |
|---|---|---|
| US/EU checked baggage (linear) | 158 cm / 62 in (L+W+H) | most airlines, oversize fees beyond |
| Typical freight pallet footprint | 1200 × 800 mm (EUR) or 1219 × 1016 mm (US) | bulk shipping efficiency |
| Stacking test | case top must support ≥3 similar cases | warehouse and transit storage |
Common mistake: choosing by external dimensions. Two 600 mm cases can differ by 15–20 % in usable internal volume depending on wall thickness, latch towers and hinge design. Always compare internal drawings, and request the foam layout, not just the shell spec.
§03Wheels, handles and ergonomics
If the loaded case will exceed roughly 15 kg, specify wheels and a telescoping handle, and confirm the wheel axle is mounted on a reinforced boss rather than screwed into thin shell plastic. For field service kits, a shoulder-strap or backpack option on the 10–20 kg class is often more practical than wheels on stairs and gravel.