The real cost of a single stockout (it's not the lost sale).

A SKU goes out of stock for four weeks. You do the math in your head: thirty units a month, $25 margin each, so about $750 of margin lost. Frustrating, but the next batch is on the way.

That number is wrong. The arithmetic is fine. You just stopped at the first line. Lost margin on the missed sales is roughly 15 to 20 percent of what a real stockout costs. The other 80 percent sits in places that never show up on a P&L line.

This is from an Australian operator running an 800-SKU Cin7 Core business in personalized gifts, weddings and corporate gifting. We've sat in the post-mortem for plenty of stockouts. The pattern holds: the visible cost is small, the invisible costs compound for months, and the ops team underestimates them every time.

Here are the seven costs of a single stockout, with rough numbers you can plug your own data into.

1. Lost margin on the missed sales

The visible one. Whatever your margin per unit times whatever you would have sold during the outage.

At $50 MSRP, 50 percent margin, 30 units per month, four-week stockout: $750 lost.

This is the number most operators count. It's the floor. Everything below adds to it.

2. Lost Shopify ranking and discoverability

When a SKU is out of stock, Shopify de-prioritizes it in collection sort and in search results. Some themes hide it entirely. Even after stock comes back, the page has lost two to four weeks of ranking signal: the clicks, conversions and recency that the algorithm reads.

You can measure this by pulling the SKU's daily sessions for the four weeks before, four weeks during, and four weeks after the stockout. The "after" figure typically takes two weeks to recover to baseline. Conservatively, plan for 20 to 40 percent of normal sessions lost in the recovery window.

At our $50 example, that's another 10 to 15 units of missed sales after the SKU is technically back. Call it $300 of margin.

3. Customer switching

This is the one that hurts most over time and gets counted least.

A customer who can't buy from you today buys from someone else. If they like that product, they buy from that competitor next time too. What you've lost is the next three to five years of their purchases in your category, not one transaction.

For repeat-purchase categories like corporate gifting and milestone gifts, this is brutal. A customer worth $400 in average lifetime value, who switches because they couldn't buy on the day they needed it, takes the full $400 with them. Not $50.

Assume one in seven of your stockout-affected customers genuinely switches. At 30 stockout-period customers, that's 4 switches × $400 = $1,600 of LTV erosion.

4. Rush freight and expedited PO premiums

When the panic order goes out, the price changes. Air freight instead of sea, expedited supplier production, smaller minimum order quantities at worse per-unit pricing, and a premium on top for "we need this in 10 days, not 30." Every line of it costs more than the order you should have placed a month earlier.

A 1,000-unit replenishment that normally lands at $5 per unit might cost $15 per unit by air. On a 100-unit emergency drop-ship from a domestic backup supplier, you could pay double the per-unit cost just for speed.

For our $50 example, assume a 200-unit rush order at $4 per unit over normal cost: $800 extra.

5. Customer service load

Every stockout generates emails. "Is this back in stock?" "When will you have it again?" "Why did you let me check out and then cancel my order?" Refunds processed. Apologetic discount codes issued. Reviews to monitor.

A four-week stockout on a popular SKU at our scale typically generates 15 to 30 customer inquiries. At 15 minutes each on average and a customer service hourly cost of $40, that's $150 to $300 of pure overhead.

6. Wasted ad spend

If you're running Meta or Google ads against the product page or category, the spend keeps flowing while the product is unavailable. Some platforms eventually detect the "Sold Out" button and reduce delivery, but never fast enough.

A modest $20-per-day Meta spend on the affected SKU for the first week of the stockout before you pause it is $140 of pure waste. If the product is in a campaign that runs across multiple SKUs, the waste is harder to isolate but absolutely there.

7. Internal time and operations disruption

The operations team drops what they were doing. The procurement person rings the supplier outside cadence. If the SKU is a component in a BOM (parent SKU consumed by an assembly), every dependent finished good is potentially affected. Production schedules shift. Packers move to other lines. In-progress orders get re-quoted with later ship dates.

Hard to put one number on, but $300 to $800 in opportunity-cost-equivalent time for a single significant stockout is normal.

The full count

Here's the running total for one four-week stockout on a $50 MSRP product that normally generates $750 of monthly gross margin:

Cost	Amount
Lost margin on missed sales	$750
Lost Shopify ranking recovery	$300
Customer switching (LTV erosion)	$1,600
Rush freight / expedited PO	$800
Customer service load	$250
Wasted ad spend	$140
Internal time disruption	$500
Total	$4,340

The visible cost was $750. The real cost was $4,340. The multiplier was about 5.8×.

Now multiply that by the number of stockouts your business has per quarter. For an 800-SKU operator running on gut-feel reorder management, 8 to 15 stockouts per quarter is typical. That's $35,000 to $65,000 of avoidable cost every three months.

Why operators systematically underestimate

The first cost is the only one with a line item. Lost margin appears (sort of) in your sales reports. The other six are spread across customer service tickets, ad accounts, supplier invoices, and "we'll do it next week" lists. Nothing aggregates them.

Most of the costs are deferred. The Shopify ranking dip doesn't show up until two weeks after the SKU is back. The LTV erosion doesn't show up until next quarter. By then you've moved on to the next problem.

And stockouts feel like bad luck. "Supplier was late," "weather hit the container," "demand spiked." So you absorb the cost and don't change the process. Then it happens again.

It isn't bad luck. A reorder point set too low, a lead time you trusted that ran long, a buffer stock sitting at zero. Those are knobs you can turn.

The math that prevents most stockouts

The reorder point you need on any SKU is roughly:

reorder point = avg daily demand × lead time × (1 + safety multiplier)

Three inputs, each one recoverable from your own data.

Average daily demand is your trailing 12-month sales divided by 365. For a SKU that sold 360 units last year, that's roughly one unit per day. Use a longer window for seasonal SKUs and add a seasonal lift for known peaks.

Lead time is business days from "supplier confirms order" to "stock available to sell," including freight and goods-in processing. Most operators stop at the supplier's quoted lead time. The real number is usually two to five days longer once you count your own warehouse delay.

Safety multiplier is a buffer. With 12+ months of stable data, 0.5 is reasonable. With 3 months of data and a noisy demand profile, double it.

A SKU that sells 1 unit per day, has a 14-business-day lead time, and a 0.5 safety multiplier needs a reorder point of 1 × 14 × 1.5 = 21 units. Order when stock drops to 21. That number is the difference between "covered" and "out for two weeks."

Plug your own numbers in for every SKU that's stocked out in the last six months. You'll usually find the reorder point was set at half of what the math says, either by default or by hand. Adjust it upward and most of those stockouts don't repeat.

What to do this week

Three actions, in order.

One. Pick the three SKUs that stocked out most recently. For each, calculate the seven costs above using real numbers from your store. Show the total to whoever signs off on reorder timing. Once they've seen the multiplier once, nobody counts just the missed margin again.

Two. For those same three SKUs, recalculate the reorder point using the formula above. Compare to the value currently in Cin7 Core. If yours is significantly lower than the calculated value, that's where the next stockout is queueing up. Update it.

Three. Pick one SKU you've never stocked out on. Calculate its reorder point. If yours is too high, you've been ordering too early, with money tied up in stock that didn't need to be there yet. The same math catches both failure modes.

Count the whole bill

A stockout isn't a 15 percent margin event. It's a 100 percent margin event that you only counted 15 percent of.

Holding a few extra units of cover is cheap. Running out is not. Go and recalculate the reorder point on the last SKU you let run dry.