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MarginLab

30 Business Article · Inventory & Working Capital

Your Supplier Offers 10% Off if You Buy Twice the Inventory. Is It Actually a Good Deal?

Paying less per unit sounds like an automatic win. But a larger purchase order ties up more cash, extends inventory exposure and increases the cost of being wrong about future demand.

Inventory Supplier terms Working capital Cash flow

The supplier is offering you a better margin. They are also asking you to take more inventory risk.

Your usual order is 1,000 units at $20 each.

The supplier offers a 10% discount if you order 2,000 units instead.

Unit cost falls to $18.

At first glance, that looks excellent. You save $2 on every unit.

But the purchase order does not get smaller. It gets much larger.

You now commit $36,000 instead of $20,000, locking an additional $16,000 into inventory before knowing exactly how quickly it will sell.

The normal purchase cycle

Assume you normally buy 1,000 units at $20.

Units purchased 1,000

Normal supplier order.

Unit cost $20

Standard purchase cost.

Cash required $20K

Before freight or other purchasing costs.

Monthly sales 500 units

Illustrative current demand.

Compare the two purchase orders

The bulk order saves money per unit — but requires 80% more cash.

Normal order 1,000 units
Unit cost $20
Purchase value $20,000
Months of stock 2 months
Cash committed $20K
Supplier deal 2,000 units
Unit cost $18
Purchase value $36,000
Months of stock 4 months
Cash committed $36K
The hidden price of the discount

You save $4,000 on 2,000 units — but commit $16,000 of extra cash.

Buying 2,000 units at the original $20 cost would require $40,000.

At the discounted $18 price, the order costs $36,000.

So the purchasing discount is worth $4,000.

But compared with your normal 1,000-unit order, the business must still send the supplier an additional $16,000 today.

That extra cash cannot simultaneously fund marketing, payroll, another SKU, a new supplier or an unexpected operating problem.

Additional cash tied up $16,000

The deal reduces purchase cost per unit, but materially increases the amount of working capital committed to this SKU.

The deal depends on what happens next

Same discount. Three very different outcomes.

Scenario A Demand stays strong
Monthly sales 500 units
Sell-through time 4 months
Markdown required $0
Likely outcome Good deal
Scenario B Demand slows
Monthly sales 350 units
Sell-through time ~5.7 months
Extra inventory exposure Higher
Likely outcome Questionable
Scenario C Demand breaks
Monthly sales 200 units
Sell-through time 10 months
Markdown / dead-stock risk High
Likely outcome Potentially bad deal
What the 10% discount does not show

Inventory has costs even before it becomes dead stock.

01
Opportunity cost

Cash committed to extra inventory cannot be used for another product, advertising, supplier payment or growth opportunity.

02
Storage and handling

More units occupy more warehouse space and can increase handling, insurance and fulfillment complexity.

03
Demand uncertainty

Four months of inventory requires a stronger forecast than two months. More time means more opportunity for demand to change.

04
Markdown risk

If sell-through weakens, the discount received from the supplier can be smaller than the discount eventually given to customers.

05
Obsolescence risk

Fashion, seasonal, technology and trend-sensitive products can lose value long before their physical condition changes.

The simplest economic test

Compare the purchasing saving with the cost of carrying the extra inventory.

Supplier saving $4,000
−
Extra inventory costs ?
=
Real economic benefit ?
The $4,000 purchase saving is real. But it is not the final answer. Storage, markdowns, financing, opportunity cost and slow-moving inventory can consume part or all of that benefit.
Before accepting the supplier deal

Check four numbers.

01 Expected sell-through time

How many months will the larger purchase realistically remain in stock?

02 Extra cash required

What else could the business do with the additional working capital?

03 Markdown risk

How much of the supplier saving disappears if excess stock later requires discounting?

04 Forecast confidence

How reliable is demand for the additional units, not merely the units you normally buy?

Verdict in our example
The 10% discount is attractive. But it is a good deal only if the extra 1,000 units move fast enough.
At 500 monthly units, four months of inventory may be perfectly manageable and the $4,000 supplier saving can be valuable. If sales slow substantially, however, the extra stock remains on the balance sheet longer, absorbs cash and becomes increasingly exposed to markdown and obsolescence. The purchasing discount should therefore be evaluated against inventory productivity, not in isolation.
The purchasing rule
A lower unit cost is valuable. Until the inventory required to get it becomes more expensive than the saving.
Supplier discounts should improve the economics of inventory, not merely make the purchase invoice look better. The strongest deal is the one that balances unit cost, sell-through speed, cash requirements and downside risk.
MarginLab · Profit Intelligence

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