Estimate annual shipping container movement globally in TEUs

Estimate the total annual container port throughput movement (in Twenty-Foot Equivalent Units - TEUs) handled across all global maritime container ports in a year.

Context

Maritime shipping carries ~90% of global manufactured trade, measured in standard 20-foot (1 TEU) and 40-foot (2 TEU) steel shipping containers.

Clarifying questions to ask first

Are we measuring physical full containers shipped (trade volume) or total port throughput (crane lifts including empties and transshipments)? (Total port throughput TEUs).
What is 1 TEU? (A standard 20-foot shipping container).

How to approach it

Top-down by Major Trade Lanes: Transpacific (Asia-US), Asia-Europe, Intra-Asia, Transatlantic, and North-South Trade
Port Handling Throughput vs Physical Container Fleet: Differentiate physical shipping containers in existence (~30M TEUs) from Total Port Moves / Throughput (~850M TEU port lifts/year)
Account for Transshipment Hubs (containers handled multiple times at hub ports like Shanghai, Singapore, Rotterdam, Dubai)
Synthesize global container port throughput TEU volume

Framework: Global Port Throughput (TEUs) = Physical Loaded TEUs Moved × Average Port Handlings per Journey (Transshipment Factor)

Sample answer

Physical Loaded Global Container Trade: ~180 Million loaded TEUs moved per year
Transshipment & Empty Repositioning Multiplier: Each container is handled an average of 4.5 times (Origin Port -> Transshipment Hub 1 -> Transshipment Hub 2 -> Destination Port -> Empty return)
Total Global Port Throughput = 180M physical TEUs × 4.7 handlings = ~850 Million TEU moves/year
Top Ports check: Shanghai (47M TEU) + Singapore (37M) + Ningbo (33M) + Shenzhen (30M) = Top 10 ports alone handle ~300M TEU

850 Million TEUs handled annually across ~500 commercial container ports globally

Executive estimate: ~830 to 860 Million TEUs handled annually at global container ports (originating from ~180M physical loaded container shipments).

What interviewers look for

Global Physical Container Fleet (~30M TEUs)
Port Throughput vs Physical Fleet Distinction
Major Global Trade Lanes Sizing
Transshipment Multiplier Factor (~2.5-3.0 lifts per journey)