Packet sizing is math, not habit
The single most common B2B sizing mistake is picking a packet size by what 'looks right' instead of by calculation. The math is not difficult: DryGelWorld silica gel adsorbs up to one-third (33%) of its own weight in water vapor. A sealed carton of internal volume V (in cubic meters) at average export humidity holds approximately V × 20 grams of water vapor. To control that, you need silica gel weighing at least 3× the vapor mass (i.e., V × 60 grams). Adjust upward for high-humidity destinations, long voyages, and weak packaging barriers; adjust downward for short routes and tight packaging. Once you have the calculation, sizing becomes mechanical.
- Silica gel adsorbs ~33% of its weight in water vapor.
- Sealed carton vapor load: ~V × 20g where V is carton volume in cubic meters.
- Minimum silica gel: 3× vapor load → V × 60g.
- Adjust for route, voyage length, and packaging quality.
Sachet size cheat sheet by carton volume
For practical B2B sizing, here's the working table by carton volume. Small unit pack (0.001-0.01 m³, e.g. consumer electronics box): 0.5g-1g sachet. Standard product carton (0.01-0.05 m³, e.g. small retail box): 2g-5g sachet. Medium product carton (0.05-0.1 m³, e.g. typical export carton): 5g-10g sachet. Master carton (0.1-0.5 m³): 25g-50g sachet. Large export carton (0.5-1 m³): 50g-100g sachet. Pallet-level supplementary protection: 250g-500g bag at pallet base. Container ceiling: 1kg-5kg multi-chamber cargo strips, 4-6 strips per 40ft container on long-haul routes.
- Small unit pack (0.001-0.01 m³): 0.5g-1g sachet.
- Standard product carton (0.01-0.05 m³): 2g-5g sachet.
- Medium product carton (0.05-0.1 m³): 5g-10g sachet.
- Master carton (0.1-0.5 m³): 25g-50g sachet.
- Large export carton (0.5-1 m³): 50g-100g sachet.
- Pallet level: 250g-500g supplementary bag.
- Container ceiling: 1kg-5kg strips, 4-6 per 40ft container.
Route adjustments — when to size up
The base sizing math assumes standard conditions. Real-world routes deviate. Tropical-to-temperate long-haul (Karachi → Hamburg, ~25 days): increase sizing 50-100% over base. Trans-Pacific (Karachi → Vancouver, ~30 days with storm cycling): increase 75-100%. Cross-equator (Karachi → Sydney, ITCZ crossings): increase 50%. Intra-region short routes (Karachi → Jebel Ali, ~7 days): use base sizing or even reduce 20-30%. Multi-month warehouse storage at destination before final use: increase 30-50%. Buyers running long-haul export programs to Europe or the US almost always need larger sachets than the base table suggests.
- Tropical-to-temperate long-haul (~25 days): +50-100% over base.
- Trans-Pacific (~30 days with storm cycling): +75-100%.
- Cross-equator with ITCZ: +50%.
- Intra-region short routes (~7 days): base sizing or -20-30%.
- Multi-month destination storage: +30-50%.
Product sensitivity — what cargo actually needs
Different cargo types have different moisture tolerance, which changes sizing. Precision electronics (PCBs, MSL 2-3 components): high sensitivity — size at upper end of base table, plus container-level strips. Leather and footwear (mold-sensitive): high sensitivity, especially on long-haul routes. Pharma packaging (regulated): size against the product's documented stability range, not just the carton volume. Cost-tier industrial durable goods (machinery parts): mild oxidation risk — base sizing or slightly below. Food packaging (food-grade context): base sizing; food-grade compliance is a separate documentation question. Match the sizing aggression to cargo damage cost — high-value cargo deserves over-sizing, low-value durable goods don't.
- Precision electronics: upper-end base sizing + container strips.
- Leather/footwear (mold-sensitive): upper-end on long-haul routes.
- Pharma packaging: size against stability spec, not just carton volume.
- Cost-tier industrial: base sizing or slightly below.
- Match sizing aggression to cargo damage cost.
Format matters as much as weight
Picking the right sachet weight is half the decision; picking the right format is the other half. Breathable paper sachets (DryGelWorld default) work for most B2B applications — clean low-dust packaging, good print surface, B2B-appropriate cost. Woven or non-woven bead bags for larger formats (25g+). Multi-chamber cargo strips for container-ceiling placement (1kg-5kg). Tyvek format for cleanroom-grade pharma (on the expansion roadmap; not yet in DryGelWorld catalog). For pharma bottle inserts specifically, look at the pharmacopoeia-compliant insert pattern for your destination market — the format and material requirements vary.
- Breathable paper sachets: B2B default, 0.5g-10g range.
- Woven / non-woven bead bags: 25g+ formats.
- Multi-chamber cargo strips: 1kg-5kg container ceiling.
- Tyvek: cleanroom-grade pharma; expansion roadmap, not yet in catalog.
- Pharma bottle inserts: per-market pharmacopoeia compliance separately.
Common sizing mistakes
Three sizing mistakes recur in B2B procurement. First: using small unit-pack sachets in master cartons because they're cheaper per unit — the math doesn't work, you'd need 10+ small sachets to equal one properly-sized 25g. Second: using container strips alone without carton-level sachets — strips manage container-air humidity but don't protect cargo inside each carton from micro-environment moisture. Third: ignoring route adjustments because 'the supplier said 5g works' — supplier defaults are conservative for standard short routes, not for tropical-to-temperate long-haul. Avoid all three by doing the sizing math explicitly per shipment, not by inheriting it from the previous shipment.
- Mistake: small sachets in master cartons (10× more cost-effective to use 1 properly-sized).
- Mistake: container strips without carton-level sachets (strips don't protect cargo INSIDE boxes).
- Mistake: ignoring route adjustments ('supplier said 5g works').
- Avoid by doing sizing math per shipment.
Pre-shipment validation — sample test before bulk commit
For serious procurement programs, validate sizing before locking MOQ. Order samples in the calculated size range, run a 14-30 day humidity test against representative packaging, and measure either the indicating-silica-gel color change or the carton humidity directly. If the sample sachet saturates before voyage simulation completes, size up; if it stays fresh-orange/blue at end of test, you might be over-sized and can reduce by 20-30% on the next order. This validation step adds 2-4 weeks to procurement timeline but pays back massively on long-haul export programs.
- Order samples in the calculated sizing range.
- Run 14-30 day humidity test against representative packaging.
- Measure indicating color change OR carton humidity directly.
- Saturation before test ends → size up.
- Fresh at end of test → potentially over-sized; reduce 20-30% next order.
- 2-4 weeks added timeline; massive payback on long-haul programs.