Grow Bag Container Economics: Cost Per Expanded Litre

An Indonesian cocopeat block producer packs grow bags for export on two levers: expanded litres per bag and bags per 40ft HC. Freight looks expensive until you convert each bag into expanded litres — the unit greenhouse managers actually plant into.

Example packing yields

• Standard grow bag: 800–850 g, expands 8–9 L, about 18,000 bags per 40ft HC.
• 2.5 kg growbag: expands for larger crop slots, about 9,600 bags per 40ft HC.
• Blocks: 60–70 L per 4.5–5 kg block, about 4,400 blocks per 40ft HC.

A simple comparison formula

(CIF container cost) ÷ (bags × expanded litres per bag) gives cost per litre. Run the same formula on blocks if you hydrate on site. The cheapest invoice is not always the cheapest litre in the greenhouse.

Specs that protect the maths

Lock EC, moisture, weight band, and expansion band in writing. Small moisture swings change net substrate yield and erase freight savings.