Time is money: the hidden cost of a thousand small orders.

There is an old reflex in buying: order little and often, keep inventory low, stay flexible. It feels prudent, and on the price line it often is. But price is only the visible tip of what a purchase costs. Behind every delivery sits a chain of work, raising the purchase order, receiving the goods, checking them, putting them away, matching the invoice, paying it. That work has a cost, and unlike the unit price it does not fall when the order is small. A delivery of ten units and a delivery of ten thousand units cost almost the same to receive. Place a thousand small orders and you have paid for a thousand receipts.

The classic tool here is the economic order quantity, the Wilson formula, which balances the cost of ordering against the cost of holding stock and finds the point where the two together are lowest. It is a genuinely useful idea, and it is usually taught with too few costs in it. The textbook version counts the obvious ordering cost and the obvious holding cost. The real version has to count the things that hide: the labour of receiving and inspection, the capital tied up, the space consumed, the risk of obsolescence, and, crucially, the cost of the returns and quality problems that more touches inevitably create. Leave those out and the formula will happily recommend an order pattern that is cheap on paper and expensive in the warehouse.

This is where our method earns its place. Time-driven activity-based costing puts a real number on the cost of one receipt, one inspection, one put-away, by measuring the capacity each consumes. Suddenly the question is no longer just 'what is the unit price at this order size' but 'what does it truly cost us to bring this in, all in'. The answer reshapes the decision. We have seen, in an illustrative case, a buyer move from weekly to fortnightly deliveries on a stable line and cut receiving touches by around forty percent, freeing capacity that had been quietly absorbed by the act of receiving. The unit price barely changed. The total cost fell. Figures illustrative.

None of this means small and frequent is always wrong. Sometimes it is exactly right, and the next field note is about precisely when. The point is narrower and more useful: you cannot make that call on the price line alone. Time is money, and a thousand small orders spend a great deal of it where nobody is looking.