Question 1

How does this calculator decide how much stock to order?

Accepted Answer

It weighs two costs against each other: the margin you'd miss on a sale you can't fulfil if you run out, against the loss on any unit left unsold. The quantity it suggests is the point where ordering one more unit is exactly as likely to be wasted as it is to save a lost sale, given how confident you are in your demand estimate.

Question 2

What is the newsvendor model?

Accepted Answer

The newsvendor model is a classic inventory formula for one-shot ordering decisions, buying stock once for a fixed selling window with no reorders, which is exactly the shape of a Black Friday order. It balances the cost of ordering too little (a stockout) against the cost of ordering too much (unsold leftovers) to find the quantity that maximises expected profit. This calculator is a plain-language version of that model.

Question 3

What is stockout cost, and how is it factored in?

Accepted Answer

Stockout cost is the profit you miss on every sale you can't fulfil because you ran out of stock, which this tool takes as your margin per unit. A higher margin makes running out more costly relative to overordering, so the calculator recommends carrying more stock as a buffer.

Question 4

What does "How sure are you about that?" actually change?

Accepted Answer

It sets how wide a range of outcomes the calculator plans around. **Fairly sure** narrows the spread of likely demand, so the recommended order sits close to your estimate; **Could be off a lot** widens it, which usually pushes the order quantity further from your estimate to protect against a bigger miss in either direction.

Question 5

What does "Leftover units are worth" change?

Accepted Answer

It sets how much you can recover on unsold stock, from **Close to cost** at one end down to **Nothing** if it's a genuine write-off. The less you can recover, the more expensive overordering becomes relative to running out, so the calculator recommends a smaller order.

Question 6

What if I can only order in bulk multiples, like cases of 200?

Accepted Answer

Enter that multiple in **Order in multiples of**, and the recommendation is rounded to the nearest quantity you can actually order, rather than an exact number your supplier can't fulfil.

Question 7

Where can I get help with the rest of my Black Friday stock planning?

Accepted Answer

Map your order deadline back from sale day with the [backwards planner](/tools/backwards-planner), or check whether financing the extra stock pays for itself with the [financing break-even calculator](/tools/financing-break-even). Browse every tool in the [full Black Friday toolkit](/tools).

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