Buffer stock isn't optional — it's insurance.

Most e-commerce operators treat buffer stock as a number their inventory system asked them to fill in once, never thought about, and likely set to zero. That's a mistake. Buffer stock is the cheapest insurance policy in your business, and almost nobody is paying the premium.

What buffer stock actually is

Buffer stock — sometimes called safety stock at a per-SKU level — is the minimum quantity you want to keep on hand at all times to absorb unpredictable variance. It's not the same as your reorder point. The reorder point says "order more when you cross this." The buffer says "don't ever go below this; treat it as out of stock."

A SKU with buffer = 1 and available = 1 is, operationally, out of stock. You shouldn't sell that last unit because if it goes wrong (damaged, lost, miscounted), you're at zero with no time to recover.

Why teams skip it

Three reasons, all flawed:

1. "We'll just reorder faster"

OK, but your supplier still needs lead time. If you're at zero on a Tuesday and your lead time is 14 days, you're at zero through to the next Tuesday, regardless of how fast you act.

2. "We don't want capital tied up"

Buffer of 1–3 units per SKU is rounding error in working capital. The cost of being out of stock — lost sales, customer lifetime value damage, paid-traffic waste — dwarfs the cost of holding.

3. "Our system doesn't really support it"

True for most. Cin7 Core has a min-stock field but no logic that acts on it. The threshold is just for an alert, not for the reorder calculation.

How to set it (without overthinking)

The right buffer for a SKU is the variance you can't predict. Three knobs:

• Lead-time variance. If your supplier hits ±5 days on a 30-day lead, set buffer to cover ~5 days of demand for that SKU.
• Demand spikes. If a SKU has occasional surges (a TikTok mention, a corporate order), buffer should absorb a typical surge size.
• Quality risk. If a small percentage of units arrive damaged or unsellable, buffer covers that loss.

For most stable SKUs at PF, we use a global buffer of 1 — the floor. For high-velocity, high-volatility SKUs, we override to 3–5. For seasonal hero products, 10+ during peak.

What it changes operationally

The moment your inventory system treats available <= buffer as effectively out of stock, three things change:

1. Reorder triggers earlier. You start the reorder process before you've actually run out, with breathing room.
2. Out-of-stock dashboards stop lying. A SKU at 1 unit with buffer 1 shows as OOS, which is the truth — you have one in the warehouse, not "in stock."
3. OOS-since dates become accurate. You can answer "how long has this SKU been out?" honestly, which lets you measure actual fill rate.

In Stocura, every SKU has a buffer field with a global default. The reorder engine, OOS detection, OOS-since stamping, and dashboard alerts all respect it. A SKU with available = 1 and buffer = 1 counts as out of stock everywhere — three pages, one definition.

Bottom line

If you've never thought about buffer stock for your top 20 SKUs, do it this week. The math is straightforward and the protection is real. Buffer stock is the insurance policy you don't think about until you wish you'd had it.