Estimating Warehouse Storage Capacities

Summary of Published Article

Non-specialist staff may sometimes be reduced to tears of panic during humanitarian emergencies by being called upon to estimate the storage capacities of warehouses. A recent paper published in Disasters which presents a simple method for rapidly calculating warehouse capacity may be of some assistance here.

The paper explains that simple rules of thumb like 'one tonne of storage per square metre of floor space' can give very misleading estimates of storage capacity. Because of the need for access, separation and limitations on stack height, the actual quantity which a warehouse can properly store is only a fraction of the amount arrived at using the one tonne per square metre calculation. Access is needed for inspection, moving items around in the warehouse and fumigation. Stack height will be determined by factors like size, type and strength of packaging, special characteristics of the commodity, handling methods, and floor strength. The need for segregation is determined by factors like the number of different types of commodity being stored.

Two rules of thumb that the paper is prepared to endorse are that:

1. approximately one cubic metre of net food storage space is needed per 1,000 beneficiary days supply of a typical food ration. This figure excludes all space lost due to access, segregation and housekeeping, and
2. a typical issue of non-food items takes up as much volume as a three week food supply for that same population (although it only weighs as much as a one-week supply of food) The paper concludes by providing a four step tool (in the form of a grid) for calculating warehouse capacity based on warehouse length and width, aisle space, mix of food and non-food items, and stack height. This tool, known as the 'warehouse capacity estimator' appears fairly user-friendly.

This article is published in an article entitled 'Estimating Warehouse Capacities', in Disasters Volume 21, No 2, pp 155-166, June 1997.